If the device contains support for the font's, you just need to change the
font associated with the EDIT controls. At run-time, figure out what font
you want to use and assign that to textBox1.Font (or whatever control name).
I'm not sure what you mean by saying that "there are polish fonts in the
app". Fonts aren't in an application, as far as I can think... As far as
data entry of Polish characters, you'll have problems with that unless you
have some means of entering the right characters (a Software Input Panel or
something, which you'd have to write yourself).
Paul T.