Hi Yaya Hong,
Good day. Your problem sounds like your sticky notes is stuck off screen everytime it starts with OneNote. Try to repair the app first.
- Go to Settings > Apps > Installed apps > Sticky Notes > Advanced options.
- Click Terminate, then Repair. Restart the PC and check if the gray window still moves to the far right.
- If it continues, return to the same page and select Reset. Note that this may remove locally stored Sticky Notes data, so don't use it yet if you have notes that aren't synced.
- If needed, also go to OneNote > Advanced options and select Repair, then restart the PC.
If this happens when Sticky Notes starts with Windows, try to check the Startup apps and temporarily disable Sticky Notes.
Regards,
Jhun