I run my iPad in German but I am used to work with photoshop in English. Sometimes it’s hard to understand the German translations. So I would like to work with Photoshop on iPad in English as well. But I don’t see how I can change the language of the app.
Photoshop on the iPad follows the iPad's language. At this time, we're not supporting Portuguese, so you'll get the last one of the four supported langauges you used on your iPad (this is Apple's paradigm for the iPad -- I agree it's weird and doesn't match any other software context). So, if you want PS in English on your iPad, switch your OS langauge to English, otherwise, you can roll with French.
I hope that helps. Feel free to ask any follow up questions you have.