I want to use a different Microsoft account but it won't let me

I want to use a different Microsoft account but it says I have to use the first one I used which I don't have the login details to. I have to use a different PlayStation account to use the Microsoft account but it doesn't have the things I want i.e.(theme,organization,etc) I also don't want to have to switch my PS accounts every time just to play Minecraft with my friends on a different platform.