Transfering signature to new computer: export=.cer, .fdf, .p7c import only .p12, .pfx

I am trying to transfer my signature from Adobe Acrobat Reader DC on my old computer to a new one.

I am following instructions described in another post:

1.  On the old computer, pull down Edit - Preferences

2. In the Categories list, select Signatures

3. in Identies & Trusted Certificates, click the MORE button

4. a dialog opens and Digital IDs is highlighted. Select the signature in the right side of the dialog and click the EXPORT button at the top

5.  a dialog appears.  Choose "Save the data to a file" and click NEXT

6.  Select a location for the file.  Select the "Save as type" has 3 choices: *.fdf  *.p7c  *.cer

7.  On the new computer navigate to the same screen and click the Add Digital ID button

8. a dialog appears.  Select "My existing digital ID from:" and select "A file" and click NEXT

9. Click the Browse button.  It only displays *.p12  and  *.pfx  files.  Also it is expecting a password on the file, yet no password was set when the file was created.

Please clarify this process for moving signatures from one computer to another.