Hi! It sounds like you’re trying to edit a PDF in PDF Gear on your Mac running OS X 10.15, but you're being asked for a password even though you never set one. Let me help you figure this out.

Sometimes, PDFs can have password protection or editing restrictions applied by whoever created them, which might require a password to edit or unlock, even if it’s not obvious to the user.

Here’s what I suggest:

1. Confirm the PDF’s Permissions:
- Can you check if the PDF is opening normally (viewable without a password), but only asks for a password when you try to edit? Or is it asking for a password just to open?
- This helps clarify whether it's a permissions password (to restrict editing) or an open password (to view).

2. Try Using PDF Gear’s Unlocker Tool:
- PDF Gear has a free online unlocker that can remove passwords and editing restrictions for you, no need to sign up. You can upload your PDF there to unlock it for editing:
https://www.pdfgear.com/pdf-editor-reader/how-to-edit-a-secured-pdf.htm
- This tool is size-friendly and unlimited, so it should help if the permissions are restricting editing.

3. Open with Preview to Check Restrictions:
- Since you are on a Mac, try opening the PDF with the Preview app. Go to the 'Tools' menu and see if the document info shows any restrictions like editing being blocked.
- Preview sometimes lets you know if editing or copying is restricted.

4. If Password Still Unknown:
- Unfortunately, if the PDF requires a password to allow editing and you don’t have it, there is no way to bypass that within PDF Gear or Preview.
- Using the unlock tool I mentioned usually helps unless the password was set to open the file itself.

Do you know if the PDF came from another source that might have applied protection? Also, have you already tried any unlocking tool, or is this the first time?

Let me know what you find and we can work through it together! Are you satisfied with this starting point?