Baidu's signature file must be registered for 3 months before it can be signed. If you have registered for 3 months, upload the pictures you want to set as signature files to your Baidu photo album. Before that, you must create your own club, and then you can upload it to the photo album inside. After turning, find the pictures in the album, right-click the property and copy the address. Then go to personal settings to find the signature file settings, and paste the address where the picture is copied. But it must pass the audit. I hope this helps.