header and footer bug? Acrobat modifies format when inserting page number

I am using Acrobat 2017 in Windows. I create figures from PDF files for publication, and then put them together in a single PDF file with Acrobat. I want to add page numbers to the file.

After I insert the page numbers, however, the line thickness in the figures is modified. The help feature in Acrobat suggests that... ''To prevent overlapping, click the Appearance Options link and select Shrink Document To Avoid Overwriting The Document’s Text And Graphics..." However, I cannot find the appearance option in Acrobat 17, and in any case I do not know whether this would address the issue. I upgraded from Acrobat X to DC (2017), and Acrobat X does not have that problem. Is this a known bug? Any solutions? Thanks, J