Guide

1. On the left sidebar, hover your mouse cursor over the 'Appearance' option and click 'Themes'.

2. Find the WordPress theme you want to customize and click the 'Info' button inside it.

3. Tap 'Preview & Customize' afterwards.

4. Following that, head over to the left-side panel and start making your desired customizations using the provided options.

5. Once done, click 'Activate & Save'.

6. Tap 'Activate & Save' one more time to confirm your request and apply the changes to the selected WordPress theme.