CRT Emudriver retroarch issue

I’ve been trying to set up a crt emudriver pc for my crt but im struggling with retroarch. correct me if I’ve done this wrong but I have retroarch switchres set up with a 2560 x 240p super resolution and the main retroarch menu is displaying at 320x240p perfectly but when launching a game it displays stretched showing the full 2560x240 resolution?? Does anyone have any idea what I’m doing wrong? I’m using a Radeon R5 430 gpu!

Any help would be appreciated!