Would you please follow the steps below to troubleshoot?
1. Check if your file is a scanned file, for a scanned file, you need to perform OCR for it first so you can edit files.
2. Check if your file has been password-protected, you need to enter the open passwords or permission passwords so you can edit files.
3. Check if your file has been digitally signed, for a signed file, it can’t be edited.
4. Check if your file is an XFA form, PDFelement doesn’t support the function to edit the XFA form.
If this does not help, please Contact Support for more help.