Usually people with hybrid systems only want to use the more powerful card when its needed.
Like for 3D gaming.
Maybe show us mhwd
mhwd -li -l
But I would guess its PRIME.
So once again checking the things:
glxinfo | grep renderer string
prime-run glxinfo | grep 'renderer string'
If working properly the first should show the iGPU (amd) and the second the dGPU (nvidia).
In the case of steam to use the nvidia you would edit a game launch options to be
prime-run %command%
Note:
IF you really want to use the nvidia all the time … then you may be able to access an option in BIOS to disable the iGPU. This would be most preferable but is somewhat rarely available.
Alternatively you can try one of these other utilities (like envycontrol);