BTT should stop triggering actions whenever I am working in a specific app and BTT should automatically start triggering actions or listening to triggers whenever I move to a different app.
Google search is not giving me any solution.
Click on BTT's menu bar icon, and then select Disable BTT for Current App.
To disable specific global actions inside a specific app, do this:
Open BTT and make an action for what you want to prevent. For example, you have a global shortcut ⌘+F which perhaps opens Alfred, but you don't want it to happen in the Finder. In that case create a new BTT gesture in the Finder and set the trigger to ⌘+F.
Then set the action (which happens if you invoke this trigger) to simulate the shortcut ⌘+F. Essentially you are remapping the shortcut to itself, because per-app shortcuts take priority over global shortcuts.
Better than the accepted answer is to define "Use Apple Default Or Do Nothing" as the triggered action. This comes in handy if it is not possible to define the action, which will be the same as the input, for example with 3rd or 4th mouse button. And it is faster to define.
I cannot comment on the first reply because I need 50 reputation
Be sure to click the little gear next to the trigger and check off "Prevent recursive triggers" otherwise remapping a key to itself will cause BTT to crash
(remapping a key to itself for a selected application will swallow/prevent the global trigger)