In your theme editor (Customize):

1. Click the Header cart icon, and click the Edit your cart button.
2. Click the Flash cart section to open the settings.

3. Under App Blocks, set the Location to show app embeds in the Main or Sidebar column.
4. Select the Sticky option to make app embeds remain in the same position.

Set the Sticky position to the Bottom or Top of the column.

5. Click Save.