RT531B is a remote control Humax PVR-9150T, PVR-9200T, and PVR-9300T models
May one suggest that you get the manuals for the PVR you have and read about setting the display format?
This is the manual for a PVR-9150T. Check out the last button descscribed at the bottom of Page 13
If your TV shows anything but a normal picture when using its own tuner (Watching TV rather than anything form the PVR) you may need to look at a comparable setting on your TV.
Seems to be a case of RTFM
Did I say RTFM?