What do I do when someone else logs into my Apple ID

I have had the same problem. My ex. I think it’s best to try and change your password. Although those who are close maybe able to guess Or watch what it is. If you know who it is ask them to please stop, and perhaps contact apple support if you can reach them .

Check your device list to see if there is a device signed in that you don't recognize. You can remove the device using the steps in the article below. As a precaution, change your password.

Apple ID device list -Check to see where you‘re signed in.   * 

 Apple ID Password Change.   -  

https://youtu.be/LIOapHreNe4

 What to do after you change your Apple ID or password - Apple Support  -   I suggest doing this before you change your Apple ID or password.

I got a notice that someone signed into their new watch with my ID