Open the "Settings" app on your phone's screen, and in the Settings list, locate the itunesstore and appstore columns, and click on them. Then in the list, under the item of automatic downloads, click on the option of turning off "Updates". Once we turn off the automatic update of appstore here, it will not be updated automatically in the future. To update the app in future, open the appstore on the home screen. In the update section of the appstore, select the app you want to update manually.