To modify or rename an Interval Bell, follow these steps:
Tap the Timer tab (middle icon at the bottom of the screen).
Tap Interval Bells.
Select the bell you want to rename.
Tap the three dots (⋯) in the top-right corner.
Tap Rename.
Enter the new name and tap Save.
Tap Save again in the top-right corner to apply your changes.
Your updated bell name will now appear in your Interval Bells list.