Sign in with your previously connected Microsoft account

I've got a Minecraft account, when I link to my Microsoft account it keeps saying it's already connected. To what? How do I find out what it's connected to as there is nothing. Tried clearing data didn't do anything. I'm sure it's something simple but how do I find out who linked it? Thank in in advance for your help. Also quick question as confusion on web, can i apply for realms twice as want to realms running at same time rather than switch. Didn't know if I applied again on PS4 whether it would wipe one?