SE z750 firmware

[ronefx]

I am sorry if this question has been answered already but, I can not find an answer. I would like to know of anyone could tell me a site that describe the different f/w choices or if someone could just recommend a particular choice. I want to mainly be able to switch between networks an The rest of the stuff does not matter too much. I already debranded the phone earlier today and changed it from a 750i from an "a" because there were too many choices availiable, so now I am going to repay again to redo it.

Thanks for your time & help.