Because Baidu Post Bar's signature file picture needs to be officially recognized before it can be displayed normally. The normal review cycle is 2 working days, so it cannot be displayed in time.

The following are the detailed steps to set the signature file:

1. First open Baidu Post Bar, enter the attention post bar interface, click the "Settings" option in the "Personal Center" in the upper right corner, and then select "Post Bar Settings".

2. After entering the Post Bar Settings interface, select "Signature File Settings" in the middle, and then click "Add a set of signature files".

3. Next, the option of adding a signature file will pop up. However, it is limited to quoting pictures from post bars or spaces.

4. Next, enter any post bar, and after seeing the signature you like, put the mouse on the corresponding signature file picture.

5. At this point, right-click and select "Copy picture URL".

6. Next, go to the signature file and paste it directly into the corresponding location. Click the "Save" button after the above operations are completed.

7. Then it will show that it is under review, just wait for about 2 working days. After approval, it can be used normally.