I'm having problems with my toons accepting quests from NPCs and completing quests.
This was working for me until just recently. I must have messed some setting up. At present, I'm having inconsistant results. Some toons auto complete, auto accept and do nothing at all.

I have all the toons speak to the NPC before I accept, etc.

Here is what I want:
1. Toons to accept quest from NPCs when one of them accepts the quest. I don't want them to auto accept quest.
2. Toons to complete quest when one complets it. If I'm pressing shift when I complete a quest, I want all the toons to take the same quest reward.

I've tried a lot of differnet settting and nothing is working consistently.
I may have another addon with a conflict, not sure.

Here are the options I've selected for Quest and Quest completion. If anyone sees something wrong, I would appreciate a reply.

Quest:
Toon Select & Decline Quest with Team
Accept Quests
Toon Accept Quest from Team
Only Auto Accept Quests From:
Team
Master Auto Shares Quest When accepted
Toon Auto Accept Escort Quest from Team

Quest Completion:
Enable Auto Quest Completion
Quest Has No Rewards Or One Reward:
Toon Complete quest with team
Quest has more than one reward
Toon Complete quest with team
If modifier Key pressed, toon chooses Same reward
as team otherwise toon must choose own reward
I selected Shift
Override if toon already has reward selected, choose that reward.
Turn off: "Master Auto Share Quests When Accepted" - as you are selecting and declining with team; there is no point sharing a quest everyone will already have.

You are missing "Toon Must Choose Own Reward" in your description.

Apart from that, everything seems fine.

Check that your toons do not have different settings from each other. Get the settings the way you want on one toon and push your settings to all your team members and make sure that they get them (in the default chat window, they should say Jamba-Quest: Settings received from xxx).