Question: are you trying to convert some else' DWG file to fit your needs? This file has a lot of issues, a lot. Or did you decide to convert one of your own files to use all annotative?
>>>...I cant get the text size to change when in model space...<<<
What does that mean please?
Start STYLE command, select the MASTERTRIMMER text style, reset the paperspace size to 3/32" (not 1-1/2"). OK out of this pop-up.
It looks like your MLEADERSTYLE is messed up as well: open it, open that command, select the MASTERTRIMMER leader style, select any other text style then reselect your MASTERTRIMMER text style. OK out of this pop-up. Wait, you probably need to fix the giant arrow size too (you'll see if you don't).
Your sections symbols are messed up as well: why is it scaled up by 7x? Another "fixed it in modelspace" you keep writing about perhaps?
The attributes inside them also use a unique text style STYLUSB and is set a little too big at 1/4" size and will always look too big too. You can only fix this with BEDIT command. Then ATTSYNC perhaps.
Your "drawing title" block is scaled up by 8x for some reason, instead of being at 1:1 scale: it is annotative, it will resize. Is that another one of those "fixed it in modelospace" things you do that just compounds the problems later in paperspace?
And forgive me for asking, but what on earth is a 3-1/2" = 1'-0" plot scale? Where did you come up with that one, and why? How would anyone ever measure such an odd plot scale, are you selling custom scale measuring tools with your drawings? I'm curious, you are going against every drafting norm out there with is little gem.
You have a lot of work ahead of you. Post back if you get stuck, be specific about your issues, keep posting DWG files as you "fix them" too, I think you are going all about it the wrong way.