This is a configuration in the iPhone/iPad and it is easy to change by following the steps below.
1- Go to the menu
SETTINGS > GENERAL > LANGUAGE & REGION
2- Here you see something called:
Preferred Language Order
3- inside this list MAKE SURE that you have
(and not the opposite).
if needed change this order by clicking on
at the UPPER RIGHT of this window, then inside you can move up the "english" choice.
And voila, it's done, the Pix-Star Snap app should now be in English.