Several factors can cause hdmi issues.
1) Some laps control this through fn keys.
2) Nvidia cards have their own controls
3) Some TVs need to have zoom (overscan) turned off
4) Some TVs only display 1080p widths
5) If Kodi is installed it sometimes takes over control of this with window max min settings and/or res settings
so
Is there a mouse pointer on the big part of the screen, or only in the small section at the top, or not at all?
TC