After searching I did not find similar problems. Post title describes the problem but I will expand here:
I want to update my post-nav text to reflect the year for copyright.
I go to Admin > Theme > Post-nav text.
I make edits to the text in that box.
I click the green Update button.
The changes revert - text goes back to what it was previously. (Same if I attempt to change the Pre-nav text.)
I have cleared the cache, logged out and logged back in a couple of times. Have also tried simply navigating away from the Theme tab.
Site is design-realized.com
Help? Thank you in advance.