wont stay logged in

I have had mine craft on my switch for about a month on my switch, every time i login in, after a day or to ill go to play and ill be logged out, when i go to log in again i have to delete all all of my saved data because other wise when i log in it just doesnt end up actully loging in, it just goes back to how it was prior. today i went to log in and its doing the same, but i did the same routine and i cant get in please help