How to change my phone's firmware nationality? For some unknown reason the Samsung Galaxy S4 Mini (GT-I9195) I bought in Switzerland is actually a Polish version, i.e. that's the default locale which I cannot uninstall and that's why only today I was offered an OTA to I9195XXUCOD3 instead of I9195XXUCOA2 back in February. While my question basically boils down to


  can I simply download the Swiss firmware image and flash that via Odin?


I'd prefer a general (not device-specific) answer for the following points:


How to figure out whether the firmware and device of two different countries are compatible (e.g. is the hardware sufficiently identical/compatible)?
how to modify the device's nationality, i.e. is it sufficient to replace the firmware or are other steps required?
does having the device rooted help/hinder?
For Samsung devices (unbranded ones) the answers are pretty simple:


As long as the model is the same (exactly the same, even the characters after the numbers), the ROM is compatible. (Usually the bare models without any special characters after them have more international firmwares).
Yes, it's enough if you flash an international/regional firmware on top of the old one. Sometimes it needs a factory reset but usually rebuilding the dalvik-cache is the case.
It doesn't matter if your device is rooted. You may be able to flash using Mobile ODIN if you are rooted (no PC needed then) but root access is usually not needed if your bootloader is unlocked (usual case).


So in general you can flash any ROM that suits your device model.