Somebody keeps changing my password

So I usually get logged out of my account. Just as any other normal person would do, they would log back in. However, when I tried my password, it didn't work. At first I thought I forgot my password, but this kept happening again and again. I started realizing that somebody was changing the password. That's when I tried a new different password instead of my usual, they wouldn't know. Idk if this would help, but I think somebody is hacking into my account and changing the passwords.