Customise your Mac with System Preferences
You can change system settings to customise your Mac. For example, you can change the size and location of the Dock, choose a light or dark appearance, change the desktop picture, and more.
To change System Preferences on your Mac, click the System Preferences icon in the Dock or choose Apple menu 
Open System Preferences for me
Explore system preferences
Options for your Mac are organised into preferences. For example, options you can set for Spotlight are located in Spotlight preferences.
Preferences appear as a grid of icons; the icons shown may vary depending on your Mac and the apps you have installed. Click an icon to open a preference pane and see the options.
Set options in a preference pane
Each preference pane contains options you can set. Most panes include a Help button 
to click for more information about the options.
Some preference panes are locked to protect your Mac. If the lock at the bottom left of a pane is locked 
, click it to unlock the preference pane.
Find options in System Preferences
If you don’t know where to find an option in System Preferences, use the search field at the top of the window. Options that match your search text are listed, and the preference panes where they’re located are highlighted.
Customise System Preferences
Hide a preference: Choose View > Customise, deselect the tick box of the preference, then click Done at the top of the window.
Show a hidden preference: Choose View > Customise, select the tick box of the hidden preference, then click Done at the top of the window.
Reorganise preferences: Choose View > Organise by Categories or Organise Alphabetically.
If you see a red badge on the System Preferences icon in the Dock, you need to take one or more actions. For example, if you didn’t fully set up iCloud, the badge appears on the icon in the Dock; when you click the icon, the preferences are displayed so you can complete set-up.
To change options for an app, such as Mail or Safari, open the app, click the app’s name in the menu bar, then choose Preferences. Some apps don’t offer preferences.