Your laptop is not a mind reader (not yet anyway, but it's coming - lol),
It always defaults to using the integrated GPU for everything until you configure it to use the high-performance GPU for specific apps & games in the Catalyst Control Centre in Windows Control Panel
Those apps & games will then always use the high-performance GPU in all future Windows sessions.
I believe you can even configure it by right-clicking the game or app shortcut and using the context-menu, but that method may not "stick" for subsequent Windows sessions.