Stumped: Note entry

Hi forum members...

I am trying to enter both breves and crochets to the same bar (see attached) and frankly I'm stumped! When I enter the breves, MuseScore won't let me enter the crochets, and when I go the other way and enter the crochets first, it won't let me enter the breves. By saying 'won't let me' I mean MuseScore changes the bar structure to suit the note duration. I'm sure that there must be a way to do this but can't for the life of me work out what this would be. I've looked at bar and stave properties and can't find anything there that seems to work for me. If someone could help by pointing out how to do this, or point me to the correct space in the online Manual, or as I'm enrolled in the MuseScore School, point me to the relevant section...