Branding and theming not selectable (read only)

[AngeloLama]

I created my pages via UI Builder but I would like to change the default theme, which in my case is not Polaris but appears as "-", I send a screen for clarity.
I have already tried to create custom themes via "sys_ux_theme" but in any case they are not selectable.

[AngeloLama · Accepted solution]

I add my own solution so that it may also be useful for other people.
To change the theme in UI Builder I created a theme via Theme builder, changed the theme in the parent application (sys_ux_app) and then selected it in the UX Application (sys_ux_page_registry).
So it is also automatically selected in the builder

[preethigovi]

Hi @AngeloLama ,

I have tried it, but the theme is applied for instance globally rather than selected parent application.