Problem description:

When ever I open byond for whatever reason it changes my computers resolution to like 800x800 which cuts off a lot of stuff and makes me unable to edit the size of most games. Any help would be appreciated as right now I can't even open the client let alone pay anything.

BYOND doesn't change your resolution. It doesn't have any code in the engine to change your resolution.

It sounds like something in your machine is really messed up.
Do you perchance have the windows compatability mode settings enabled on the BYOND executable?