Answer by Michael for tmux disregarding the configuration file

The file ~/.tmux.conf is loaded when the tmux server is first started. So if there are existing tmux sessions, starting a new session with tmux does not result in reloading the .tmux.conf file. Try restarting tmux server: Use the command tmux list-sessions to see if there are existing sessions. Exit them (e.g. tmux attach then kill all windows and exit). Once all sessions are gone, try tmux again. This time the rebinding should work.