Click the "gear icon" drop-down in the upper right corner of Post Bar, select "Post Bar Settings", select "Signature File Settings", and enter a name and a picture link. Please note that the pictures here are only for reference to the pictures in the post bar and space, so you need to upload the QR code to the post bar or space first, then right-click to view the address of the source file of the picture and copy it into the box, and you can refer to this signature file when posting in the future.