Can't change scratch disks

I'm trying to use photoshop and I get an error that I can't start photoshop because the scratch disks are full, I haven't had this error before so I look up how to do something about it. I do the ctrl + alt thing while launching photoshop and get to the scratch disk menu, I change the scratch disk space and start photoshop, I still can't start it. I go to the scratch disk menu and I see that the scratch disk hasn't changed at all. I've tried over and over again to change it and I've looked up a lot of different things and found no solutions. I can't use photoshop anymore and I'm very frustrated, hoping to find a good solution that will finally fix my issue