Xbox app won't let me sign into the correct account

I have an Xbox account and it's my main one with everything on it BUT I also have other accounts just ones my siblings can play on so they don't ruin my actual account. But the problem is when I get onto Xbox app to sign into the account that's mine, it signs into a completely different account and I don't know what the problem is. This same account signs in perfectly fine when I'm actually on my Xbox but the problem is I don't know why it won't work with Xbox app now.

:)