I didn't download your file but here is one approach I use a lot.
1. global variable g_strZoomValue
2. form designed for the sole purpose of holding a textbox value...and on form load event, textbox value = g_strZoomValue. Make the font larger.
3. a little Zoom icon next to textboxes for people hard of sight accessibility purposes, which makes value of g_strZoomValue equal to textbox value
4. open the form mentioned in #2
Simplistic approach, takes about 5 minutes to set up.