I am trying to add an option to an already created pivot table (I didn't create the table). When I go to the list options for one it updates no problem, but this one specific list I want to add to will not update and I'm not sure what to do. Any advice?
Since you say it's a Pivot Table that somebody else created, the first step I'd take would be--if possible--go to the person who created it and find out if it's protected or something like that.
You don't give the full picture here--what's the source data, how does it get updated, etc? Another possibility would be to simply start from the raw data and recreate the Pivot Table with the capabilities and features you want.