How can I uncheck the "use same device for future launches"?
Right click on your project, and go to Run As -> Run Configurations.
Then, under Android Application -> (Your Project), go to the Target tab, and check the first radio option Always prompt to pick device.
In Android Studio: Menu Run -> Edit Configurations
and here in app tab uncheck "Use same device for future launches"
Bottom line: my ADT on Mac environment has some sort of a bug.
Edit: This "bug" is fixed on OSX Yosemite and Eclipse Luna
If you are using eclipse JUNO, exit from eclipse and it will be disabled. When you run eclipse again, and debug your project, you will prompted again for pick device and you can select another device.
来源：https://stackoverflow.com/questions/21973001/android-adt-disable-use-same-device-for-future-launches