How to use command line arguments to force custom screen resolution?

Hello. Trying to run Sims 4 on a nettop. Device is way powerful enough to run the game (7th gen i5, 8gb Ram, 2gb nvidea graphics etc. Etc) but the tv it's plugged into is fussy about display size. Have tried editing the config file to specify a resolution that I know works, but it seems to be resetting the file on startup (useful, real useful). Cannot find list of command line arguments online, but think this is likely to be the way forward. Any help much appreciated, cheers.