Question [Q] question for help and how to unlock devices LG-LS980

Hello, please can someone explain to me some things because I can't get edge and I'm confused by all that has been written, and my English is not very good.
I have in my possession the mobile LG LS980 32 GB memory and software version LS980ZVA with ANDROID 4.2.2.
Is locked to SPRINT and I want to unlock it to use it in my country, this time the phone is rooted, I do change the file build.prop and the entry
ro.build.target_operator=SPR change to OPEN(save and reboot devices) unfortunately continues to be locked, you must do something else?

Software change I didn't understand yet how to become and how, what of all the software's that have been published must try? changing software will unlock the device; I don't want to do damage to the device and for this I ask you who have more experience.

Thank you for any answer you give me