When editing a custom set of controls for an app, add a setting for "match global settings for this button". This way if you change anything in global settings for that key, it will update in all apps. Then you can tweak just 1 key that is specific to an app. For example, I have lots of apps that I all want to have the same gesture button, but maybe a different action for the froward and back side buttons. It would be great to just all share the global settings for the gesture button and then select app specific settings for others as desired.
This would save so much time, especially setting up new apps! Thanks!