I am fairly new to D&D and I am in a group with a person that likes to run every session. They talk to every NPC, skip quests, metagame like crazy (they've played the module before), make unilateral decisions for the party, and frequently brag about how their character completed a quest, or their character killed a boss. Their character is brutally overpowered compared to the rest of us and makes combat a joke. What can I do as a player, without being confrontational or being an asshole about it? How can a person that is not very confrontational use a character that would not be confrontational to take back a little autonomy? I feel like I am a companion NPC in a single player RPG at this point. Thank you!