To modify an existing timer preset, follow these steps:
- Navigate to the Timer tab (middle icon) at the bottom of the screen.
- Click on the 'Presets' tab.
- Choose the preset that you want to modify.
- Adjust the settings as needed and then click on 'Save'.
- Decide whether you want to overwrite the existing preset by selecting 'Replace existing', or create a new preset with these settings by choosing 'Save as Copy'.