When you change any of the options in the Preferences dialog box, they are stored in a folder called Toon Boom Harmony. You can copy this folder if you want to use the same preferences on a different computer.
Windows: C:\Users\[user_name]\AppData\Roaming\Toon Boom Animation\Toon Boom [Harmony Essentials\full-1600-prefNOTE On Windows, the AppData folder is hidden. To display it in Explorer, in the top menu, open the View pane and check the Hidden Items checkbox.
macOS: /Users/[user_name]/Library/Preferences/Toon Boom Animation/Toon Boom [Harmony Essentials/full-1600-prefNOTE On macOS, the Library folder is hidden. To display it in Finder, hold down the Alt key.