Box App Material Thickness Issue

So I tried to make a box…didn’t work so well. I set the material dimensions, then open the app. The slot for the lid doesn’t match the material thickness and has to be manually sized. The depth of the tabs is also way to deep for the material thickness as well. I have tried to manually resize everything and that is harder than just making the box from scratch. What am I doing wrong??? I have used multiple browsers as well. Please tell me I’m just missing an easy step. I have already ruined a few pieces of material trying to figure this out…seems that no matter what I do the thickness defaults to 11.4mm in the app and the pieces that get imported. The depth of cut does match my material though.