problem with write permissions on internal drive in High Sierra

I believe this began after upgrading to High Sierra.... sometimes, I will go to save a file from Photoshop or some other program to my main HD and it won't let me unless I sign in to authorize it. My account is set as administrator, and I went into info on my internal HD and find that only system says read and write, wheel and everyone say read only and my username is not there. I tried to add my username from the add list, and it tells me it cannot be done because I don't have the necessary permissions(I am administrator). I can also not change everyone to read and write etc... How can I fix this?

see pictures below: