Users can switch themes in this panel, where do I need to set it in the backend?

[david (David Taylor)]

To allow users to change themes via the hamburger menu, you need to install and enable this component:

Hamburger Theme Selector

This theme component currently only works with the Legacy sidebar setting, which is going to be discontinued. Please see Sidebar theme toggle as an alternative. Summary Hamburger Theme Selector adds a theme selector in the hamburger menu provided there is more than 1 user selectable theme. This selector works with both logged-on users and anonymous users. Repository Link https://github.com/discourse/discourse-hamburger-theme-selector …