I don't know if I'd say I gave up so much as didn't know it was absolutely necessary to change them. As estimated by JohnGabriel above, the dialog box opens, but the slave toon screen doesn't interact with the gossip options from there. As I keep insisting, I'm probably just dumb... but I didn't see anything in the tutorials that says "you must have a chat channel changed for 'push settings' to work", only the "set up your quest tab as so and questing's golden"

I'd tried changing the chat channels (yes, to the same thing on both toons) and password, and relogging (because I had picked up the "relog to make sure changes stick") but for whatever reason it just wasn't handling correctly. The chat channel has held this time at least so far. For whatever reason, though, the quest gossip just refuses to interact (and without knowing what's going on, I can't tell if my settings are 'pushing' correctly or if I'm still just getting the spam but no results). Also, if it helps, my master toon will auto-accept quests, and attempt to share them, but my slave toon doesn't hear about the quest unless I click on it myself. This happens with both NPCs and 'this item begins a quest' drops.

All is not completely lost. I have found a workaround--I installed the Monomyth addon on both accounts. With the IWT working, Monomyth just automatically grabs/completes any quest gossips it sees on both toons. I'd absolutely prefer to figure out what I screwed up in Jamba, but failing that at least I have backup.

A quick note: I apologize if I'm giving the impression that I want everyone to just hand me the answers. I like to think I fall squarely into the FAQ-topic category labelled "I can figure it out" in most cases. And I did read the sticky topics, I promise. I searched the forum a few different ways, looking to see if the question had come up before. Either my Google-fu has failed me (an option I readily admit may be the case) or I'm not as bright as I'd like to believe and just totally skimmed over my answer without really seeing it. I do appreciate the help, Khatovar, as well as the list for 6-year-old me (since whether or not my custom chat was working before, it certainly is now).