how to turn off 4g and run evdo/3g?

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http://androidforums.com – i used to have huawei activa 4g and i can turn off 4g on that phone by taking the sim card off and going to lte on&off an app i download to turn on radio but anyway i go to that app and scroll down and press the radio on and it will run on 3g but in this phone it doesnt seem to work (General)