Mo. Rev. Stat. § 355.286: Votes of majority of quorum, effect.

1. Unless this chapter or the articles or the bylaws require a greater vote or voting by class, if a quorum is present, the affirmative votes of the votes represented and voting, which affirmative votes also constitute a majority of the required quorum, is the act of the members.

2. A bylaw amendment to increase or decrease the vote required for any member action must be approved by the members.