For Android 2.3 or earlier
Step 1. Find Settings on the device.
Step 2. Click Application.
Step 3. Click Development.
Step 4. Check USB Debugging Mode.
For Android 3.0-4.1
Step 1. Find Settings on the device.
Step 2. Click Developer Options.
Step 3. Check USB Debugging Mode.
For Android 4.2 or later
Step 1. Find Settings on the device.
Step 2. Find Settings on the device.
Step 3. Find Build Number and tap it for 7 times continuously.
Step 4. Go back to Settings and click Developer Options.
Step 5. Check USB Debugging Mode.