cellular data OFF connection type

Hello I would like to ask a question. When I switch on cellular data on my iPhone 5 I am able to chooe connection 2G, 3G, LTE. I am using 2g, because since they add tis option my phone was still switching between 2G and 3G an my signal went completly off very often. But my question is how my phone works when cellular data is off? Do it remember what was selected when cellular data was on (2G which is now grey option) or is it now switching from 2G to 3G like before when I couldnt choose connection? What I want to do is turn off cellular data to safe battery and also my carrier data BUT I want to stay on 2G because in location where I live my phone cant jump to 3G becaseu I will lose signal. Is it possible please? Does it stays on 2G when I turn offcellular data but I had 2G selected when it was on? Sorry for my english, it is not my native language. Thanks for any response

 

please nobody have experience with this?

 

Thank you I know about this thread but I doesnt answers my question.