Cannot select Usage Option for Digital Certificate

I've been wanting to use my self-signed digital signature / certificate for documents.  However, in looking through the instructions to set this up, i'm unable.   I followed the instructions here - Digital IDs in Acrobat DC - to import the certificate into Adobe DC for signing. However, when I click on "Usage Options" the selections are greyed out. I cannot choose one. I am signed in, and the certificate is valid through 2020. (I use it on other applications for working with the State.)

Any ideas? Searching did not help.