The un-install process has evolved through several generations of the Android OS and recent versions require several specific steps in a specific sequence to be fully effective.

Many Apps will leave the App-Data (user-configuration information) on a device, and may leave the Cached-Data as well, during an App uninstall, then "conveniently" re-apply this data to the new install. 

Since this data may be corrupted or outdated it must be removed to ensure the new installation will not be affected.

The full procedure is as follows:

  2. Select the app to be un-installed.
  3. Select "CLEAR CACHE".
  4. Select "CLEAR DATA".
  5. Select "UNINSTALL".

To re-install an Android App:
  1. Go to the Google Playstore and re-download / re-install the app.