Thanks!

I opened the website in chrome incognito window and I only tried a new tab in the same incognito window...

I uploaded 1.png as profile cover and it worked correctly. Then I uploaded 2.png as profile cover, but when I refresh the page, the cover changed back to 1.png.

I checked public/uploads/profile/XXX_profilecover in the file system, it's 2.png.

I tried these actions in this community, I worked well. I have no idea how to solve this problem.

Can anyone tell me what may be wrong?