Language Support - Spanish Not Selectable

On “Language Support,” I installed Spanish as well as English, but now the Spanish dialects (“Esp. Argentina, Esp. Mexico,” etc) appear under “Language for Menus and Windows” in a
light grey and cannot be selected or dragged up in order of preference. So I can still only set English as my language for menus and windows.

you have not put for which version of the system…

In LXQt change it in regional settings

If you want to ask in Spanish, you can do it here → en español - Lubuntu Discourse