Instead of searching for themes in the theme dashboard, you can edit your current theme from the site editor. To learn more about editing a theme from the site editor, watch the video below or follow the step by step instructions:
On the left editing panel, click on the Site Editor, then click on Styling
Click on the current theme to pull up the Theme Selector
Hover over your theme
The Edit button will appear
Click on Edit
The Theme Editor for your current site's theme will open in a new tab