MacMost: System Preferences

How To Customize App Window Toolbars On Your Mac
Most Mac apps have toolbars at the top of each window with a collection of buttons and other controls. You can customize these toolbars, adding more buttons, arranging them and removing them. You can always easily revert to the default set. Some apps, like the Finder, even let you do more with toolbars.
Learn How To Use Dictation On Your Mac

In macOS Catalina enhanced dictation is now part of Voice Control as part of your Mac's Accessibility features. It has several improvements over previous version of macOS dictation, including several ways to work to correct text, move the cursor, make selections and type difficult words.

Using Your Own Photos Or Graphics As Desktop Backgrounds
You don't have to settle for using Apple's images as your desktop background. You can use any photo from your library or image you can obtain as a desktop background. You can also make your own graphics in an image editing app or Keynote to use as a background. You can combine photos and graphics to make an ideal background.
2 Ways To Quickly Switch Between Light And Dark Mode On Your Mac
If you like to switch between light and dark mode frequently, you can create a keyboard shortcut or Dock icon to do it with one fast action. By using a very simple workflow in Automator, with no scripting required, you can create either a Quick Action or a application for your Dock. The Quick Action can then be assigned to a keyboard shortcut.
Screen Time and Parental Controls In macOS Catalina
A new feature in macOS Catalina is the ability to track and restrict your app usage. You can use Screen Time for yourself, to attempt to limit your use, or as parent controls on a standard account on your Mac. You can also limit individual websites.
How To Change Your Mac User Account Picture
You see your Mac user account picture every time you log in to your Mac. You can customize this image easily in System Preferences with some default images, a photo, or any graphic you want. You can choose a photo and zoom in on one part of the image. You can create your own graphics or download an image to use.
Customizing Your Mac Login Screen
Most Mac users never take the time to customize their login screen. But there are several options there you will want to change to increase security or have the login screen better fit your needs. There is one very easy change that every user should make, to include a message on the login screen in case you lose your Mac and want to increase the chances that it will be returned to you.
How To Use Mac Hot Corners
Hot Corners are shortcuts that you can set so an action is performed when you move the cursor to one of the four corners of your screen. You can set these up in System Preferences if you know where to look. You can use them to instantly put your Mac to sleep, trigger Mission Control and other actions. You can also set them to work only with modifier keys. There is a trick to knowing which corners work in a multi-screen setup.
Removing Annoying Alerts By Setting Notification Alert Styles
Many apps will give you alerts that appear in the upper right corner of your Mac screen. You can set whether these alerts need you to click on them to dismiss, or they dismiss themselves automatically, or they don't appear at all. The settings for this are in System Preferences, under Notifications.
Quickly Switching Between Light and Dark Mode With NightOwl

Dark Mode in macOS Mojave is a great new feature, but Apple didn't give us a way to quickly switch between light and dark modes. The little donation-ware app NightOwl gives you that control in your menu bar. You can also set a keyboard shortcut, select apps to stay in light mode, and set specific times to switch between modes.

Multiple Screen Display Arrangement
If you are using more than one screen with your Mac, you can set where each screen is located relative to the others in your desktop's virtual space. You can choose which screen is the main one by dragging the menu bar representation to that screen. You can also adjust the rotation of your screens to use them vertically.
Privacy Preferences in macOS Mojave
Mojave changes how apps ask for privacy settings and gives you easier control of those settings. In System Preferences, Security & Privacy, Privacy, you can see all of the permissions that have been granted to apps and change them. However, for typical users it is often hard to determine why an app needs access to a specific type of information.
Using Dark Mode With macOS Mojave
A new feature of macOS Mojave is Dark Mode. This favors light text on a dark background instead of dark text on a light background in the system and standard apps. You can see the change in the menu bar, app toolbars and sidebars, and even the backgrounds of apps like Contacts, Calendar, Reminders, Notes, Mail and Maps. Not all apps will change, especially third-party apps. Document content and images will not change either, as they keep using the true color specified in the document. You can also change the accent color used in standard interface elements throughout macOS.
Using macOS Mojave Dynamic Desktops
The new Dynamic Desktop feature will change the image on your desktop depending on the time of day, or more accurately, the position of the sun. You can see this in action by manually adjusting your Mac's time. Apple includes two dynamic desktops with Mojave, but we may see more from Apple or third-parties at some point.
A Beginner's Guide to Mac Display Preferences
New Mac users may not have yet explored their display preferences. You can stick with the native resolution for your display or choose one that shows text and graphics larger or smaller. Which setting you use is a personal preference, and it is easy to switch between them when you need something different.
Using Smart Quotes
Smart quotes will allow you to type the same double and single quote keys on your keyboard but get different curly quotes in the correct direction in your text. It uses the character before the quote to determine which character to show. You can turn this feature off and on and use Undo to get straight quotes in individual cases.
Mac Privacy Preferences
You can view and change your Mac's privacy preferences in System Preferences, Security & Privacy. You can see which apps you have installed that requested access to things like Contacts, Photos, Location and other information. You can grant and revoke privacy permissions to these apps. You can also read more about what these apps can access.
Start Screen Saver With a Button
Normally, the screen saver starts after a period of inactivity, or when you use a Hot Corner. But you can also create a button in the Dock to start your screen saver with a click. This can be a handy way to quickly lock your Mac too.
Customizing the Menubar Clock
The clock that appears on the right side of your menubar can be customized to suit your needs. You can choose what to display and even switch to a compact analog clock. In System Preferences, you can set the time to be spoken aloud at regular intervals. There are many third-party apps in the App Store that offer even more options.
A Beginner's Guide to Desktop Backgrounds
The desktop background is the large image that appears behind everything you do on your Mac. You can change it in System Preferences. You can select from many provided images, choose a solid color, or use any of your own photos as a desktop background. You can also have the desktop background automatically change from a selection of images on a regular basis.