my vids are showing in terrible quality to everyone but me??

what the title says. when i post to a new account from my new phone, the videos show up clearly to me on that phone, but to everybody else the quality is BUTCHERED. I checked on a different account, different phone and the same videos are in 240p and only show up in full HD to the account I posted them from. Does anybody know why this is happening or how to fix it???