There is nothing to do on the TV. The playback resolution is always 1080p.
What you see is the resolution of your PC. It may be that your graphics card can't output at 1080p or it is set to 720p. Go to the PC display settings and see if you can change it.Sony bravia 1080p want to change settings from 720 to 1080?
You don't. It displays whatever it sent to it, up to 1080p.