I'm using Acrobat Pro 9 and DC Reader, Windows 10 also WIn 7,8.
Stickies werer mostly created ion Pro 9, then the files read in Reader.
The behavior was that on rollover, the boxes would appear as quite long plain boxes, "Admin" (ok) and the text all readable.
What have I done?
Now the boxes appear small, with scroll bar(s) so you can't read them without clicking.
I'm a teacher using them to show answers to questions as we work through the text.
I'd tried changing the font size but that was about it. I've now tried all (I think) the options in Preferences, but none of them give the old behavior back.
Sorry for the delay in response to your query and apologize for the inconvenience caused.
Please navigate to Documents Preferences i.e. Edit>Preferences>Commenting and make sure that the following options are checked:
All the three options under the Pop-Up Open Behaviour i.e.
You can select the options, click on Ok, then close the PDF and quit Acrobat/Reader and launch it again and check with the PDF.
If the issue persists, you can reset the preferences of Acrobat, to reset the preferences, refer to How to reset Acrobat Preference settings to default. Link: https://forums.adobe.com/docs/DOC-8511
For your information, the support for Acrobat 9 is limited as it's an old version, you may refer to End of support | Reader 9 and Acrobat 9 (and earlier) Link: https://helpx.adobe.com/acrobat/kb/end-support-acrobat-8-reader.html
Hope this helps, and keep us posted with the results.