picture is to large for the tv screen?

RT531B is a remote control Humax PVR-9150T, PVR-9200T, and PVR-9300T models

http://www.humaxdirect.co.uk/rt-531b.html

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

https://www.uktv2c.com/Tuner%20Manuals/Humax_PVR-9150T_manual.pdf

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?
April 2016