Need my screen to be smaller?

I'm not even sure how to word my issue, I've attached photos for

visuals. I've Googled to no end and still haven't fixed my problem. I've

made sure I changed the resolution on my external monitor which is a

Toshiba HDTV. I've changed and played with settings under preferences on

my Mac. I've had Affinity Designer for a while now and this just

started recently. Nothing has changed. I haven't had any reason to mess

with my resolutions since setting up my TV years ago. Even if I adjust

the overscan, the AD menus still go off the screen. I only seem to be having issues in Affinity Designer.

Does anyone know how to fix or point me in the right direction? Thanks!