【Updated: 】
If you cannot update the app, please try the following steps without deleting (uninstalling) the app.
■ Steps
1. Launch the App Store, and tap the Apple Account icon in the upper right.
2. Scroll down until you see either "Pending Updates" or "Upcoming Automatic Updates" and check to see if an "Update" button is displayed next to Fire Emblem Heroes.
3. If an "Update" button is displayed, tap the button and update the app.
Note: Option names and other wording may vary depending on your OS version.
If an "Update" button is not displayed in step 2, refresh the information on the Apple Account screen by swiping the screen downward