I was using Samsung Galaxy with android, then I bought the new Motorola DROID RAZR using same SIM card.
when I'm trying to download any app from Google Play Store, it still refers to my previous device. How would I update my device information?
You can visit the accounts page in your computer and click on "Settings" tab. Under "My Devices" section you will have all the devices that your account is being tied with.
Common causes that prevent your device from being presented at your devices list are:
The first one probably solves your issue of registering the device within Google Play Store.
After, you can manage your devices and disable the old one. Access your account, click the "Settings" tab and untick the "Shown in menus" checkbox.
References: Google Play Help
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