Different note values ​​on top of each other

I was trying to transcribe a piano piece from Youtube when I across this issue. In the first picture (the example from Youtube) The Bb in the bass is a half note, and has to quarter notes under it (F and then E). But in MuseScore, I can't do that. I need to "convert" the half note Bb into two quarter notes. Is there anyway to fix this?