Druid Plant Shape Question

Having gone through the game countless times, I am finally doing so as a druid. I’m at level 12 now, and acquired the Plant Shape feat. It seems random as to whether I end up as a Shambling Mound or Treant.

I’d really like to select the Treant when I’m involved in melee, but I get Shambling Mound nearly every time now. How do I select which I use?

normally you should be able to select which shape you want to transform into. you already tried to drag the feat to the quick slot bar and activate it from there?

I tried to drag it there before and was unable. After reading this, I tried again- worked perfectly! Thank you!