stuck on my 2017 account…

i logged into my old musical.ly / tiktok account from 2017 to pull up old videos and now it wont let me switch back to my main account

ive tried multiple emails including one i know isnt connected to any other account because i just made it a few days ago, and ive tried my phone number, but everything just says i cant change my settings for security reasons?? what do i do??