I added the font "Open Sans" to my fonts in Adobe CC and it works just fine on all my Adobe applications except for Acrobat. It worked just long enough for me to type 3 characters before it switched to "Geneva."
It's still available in the font list and I can click it but cannot actually select it. Every time I click it, the font gets set to "Geneva" instead. I've tried all the troubleshooting suggestions available in help articles but nothing has worked.
Create PDFs, Edit and convert PDFs, General troubleshooting