To modify an existing timer preset, please follow these steps:
Go to the Timer tab (middle icon) at the bottom of the screen.
Tap the Presets tab.
Select the Preset you would like to modify.
Adjust the settings as needed.
Tap Save.
Choose either Replace Existing to overwrite the current preset, or Save as Copy to create a new preset with the updated settings.
Your changes will be saved based on the option you select.