In the Table of Contents settings I keep changing the Style at the top of the screen (see orange highlight below in screenshot), but after I click Ok (and/or Save Style) and open back up the TOC, the same previous paragraph style is reverted to in the orange highlighted area. Any ideas why? (InDesign CC)
This is a guess because I am not field-testing it, but you are including H2 in your TOC and assigning your Title to an H2. Try a style that not being used. If that works, create a style called "TOC Title" that can look like H2 and use that instead.