You can access your App Tamer preferences from the utility menu. Just control-click on App Tamer's icon in the menubar or click on the gear icon in the lower right corner of App Tamer's window, then select Preferences from the menu.
The preferences are split into five tabs, as follows.
Automatically start at login
Turn on this checkbox to have App Tamer automatically launched when you log in.
Show App Tamer in the Dock
App Tamer can appear in the Dock as a regular application, or you can turn this checkbox off and access it solely from its icon in the menubar.
Show App Tamer icon in the menubar
This turns App Tamer's menubar icon on and off. You'll generally want to keep it on because it provides quicker access to App Tamer's controls, as well as a useful indicator of how much CPU is being used.
Colorize the icon as CPU usage increases
As applications use more CPU, App Tamer's icon in the menubar will go from black-and-white to yellow to red. This gives you a quick indication of how much CPU is being used, allowing you to easily see when an application is monopolizing your processor.
Display CPU usage next to the icon
When this option is on, App Tamer will show you the percentage of CPU being used as an exact number.
Do not slow or stop apps if power is plugged in and battery is charged above X%
If you're using App Tamer primarily to conserve battery power on your laptop, turning this option on will make it slow and stop your applications only when power needs to be conserved. This will lengthen your runtime while on battery and speed recharge time when you plug back in.
You can fine-tune this setting by choosing the percentage of available battery charge at which App Tamer stops managing your apps.
Wait X seconds before slowing or stopping an app
This is an important setting. You generally want to leave a delay between the time an application is sent to the background and the time when App Tamer stops it. Many applications don't actually put data onto the clipboard until they're in the background, so you need to give them time to do this. Also, many people will click in a web browser to start downloading a file and then switch away, but the download doesn't actually start for 5 or 10 seconds. Allowing a little time for 'things to settle' will make your App Tamer experience much smoother.
Wait X minutes for apps to launch
App Tamer gives an application a certain amount of time to launch before it will consider stopping it. If you double-click on Photoshop, for example, and then switch to another app while you're waiting for Photoshop to finish launching, you want App Tamer to let Photoshop complete its startup processing. Make sure this setting is long enough to allow that to happen.
Wake stopped apps every X minutes
Applications and OS X need a little time every now and then to take care of routine maintenance tasks, cleanup, etc. App Tamer wakes all applications for an instant to allow these things to happen. This setting determines how often it does that.
Hide applications when they are stopped
This setting lets you automatically hide all of the windows of a slowed or stopped application to indicate that it's not running and to keep it out of the way. Clicking on the application's icon in the Dock or using command-tab to switch to it will bring it back into view and wake it up.
Notify me whan an application exceeds X% CPU for longer than Y seconds
App Tamer will notify you whenever an application uses an excessive amount of CPU, where "excessive" is defined by these numbers.
The alert will give you the option to allow the usage to continue for the time being, slow or stop the app, or permanently ignore any further excessive usage.
Don't notify me about these applications
Adding an application to this list will prevent App Tamer from warning you about its CPU usage, even if it goes above the notification threshold.
Note that when you get a notification about an app and choose to ignore its high usage, the application is automatically added to this list. To turn detection back on for that application, return here and remove the app from the list.
Warning: Setting a low notification threshold will cause App Tamer to use more CPU time itself, as it has to monitor all of your applications more closely.
Update CPU statistics every X seconds
This determines how frequently App Tamer updates its CPU statistics. The more frequently you choose to update the stats, the more CPU time App Tamer itself will use. We recommend setting the interval to 3 seconds or more.
Calculate average CPU over X seconds
App Tamer's calculates average CPU usage by measuring each application's CPU usage over a certain period of time. This menu allows you to select that length of time.
App Tamer's main window is normally light colored, in keeping with the rest of the macOS user interface. Previous versions of App Tamer used a dark appearance, and you can choose that if you prefer it. Note that the dark appearance will also be used automatically if you choose "Dark menu bar and Dock" in the General settings in System Preferences.
Automatically check for updates
We periodically update App Tamer with new features and compatibility fixes. Turning this option on will allow App Tamer to contact St. Clair Software to check if there is a new version available. You can use the menu to tell it how often to check (hourly, daily, weekly, or monthly).
The Check Now button does exactly that - checks immediately to see if there is an update available.