I've just updated InDesign to CC 2017 and have found that I can no longer change any settings in the Export PDF dialogue box. It's probably something simple, but it's got me stumped. Any ideas?
Do it "factory reset" - There is a quick and easy method for doing this using the keyboard: close and relaunch InDesign, and IMMEDIATELY hold down Ctrl + Alt + Shift (Windows) or Cmd + Ctrl + Opt + Shift (Mac), and respond in the affirmative to the dialog asking if you really want to replace the preferences.
Thank you, George. It's strange that this was occurring in a brand new, fresh install of the application, but your fix worked a treat. Thank you again!