Why I can’t insert signature

Hi @Meibin29280770r03a,

Hope you are doing well. Sorry about your experience.

Would you mind letting us know the error or the issue you see when inserting a signature? 

You can try the given steps to insert a signature on a document (given that the document is not read-only or locked):

1. Open the Acrobat mobile app on your device.
2. Open the PDF document that you want to sign.
3. Tap the "Edit" icon (pencil icon) in the top right corner of the screen.
4. Tap on the "Sign" (pen icon) at the bottom of the screen.
5. Choose "Add Signature" from the options presented.
6. Follow the on-screen instructions to create your signature. You can either sign using your finger or stylus or choose an existing signature from your library.
7. Once you have created your signature, place it where you want it to appear in the document.
8. When you are finished, tap "Done" in the top right corner of the screen to save your changes.

Hope this helps.

-Souvik