Flags switching colors

When I flag email messages, I always choose teal, but the flags almost always turn to red. I did some research and found that if I turn off and re-enable iCloud sync, the problem should be solved, but it wasn't. Spoke to my son, the computer genius, and he explained the problem. I'm using AOL mail, and AOL is among the providers that doesn't have the ability to differentiate colors, so it defaults to red. One of my flagged messages remained teal, and I discovered that it was on my iCloud mail account, so didn't change. Further, for any emails flagged on my Mac, they will stay teal, because this process is done locally to the machine. The ones on the phone won't, because of some technical reason that made sense at the time, but that I couldn't possibly articulate. LOL. Hope this helps!