Regardless of what I set Preferences > Code style > General > Tab size to PC steps 2 spaces when tab key is pressed in all of my open projects. I restarted PC but same. Although all Schemes show 4 for tab size I was able get PC to use 4 spaces per tab by returning scheme to Project, Default or Default(3). So it appears Default(1) was malfunctioning so I deleted it but before deleting it I checked my other projects and they all had been assigned to Default(1). I did not do that intentionally. When I set the scheme to Default in one project most of the other projects also changed to Default.
I was thinking that items under Preferences > Project settings (project) pertained to the mentioned project only. Is this not how PC Preferences works?