Changing skin within a Kodi build

I have Kodi with No Limits Build. Within the No Limits Build how do I temporarily change the skin to Estuary and then back to Aeon Nox skin with the settings for Aeon Nox skin unaltered? I have looked at all the menu options that I thought might allow me to do this but I must be missing something probably quite simple! Can anyone help?

Open KodI and click on System. Then click on Interface. There are you will find Skin. Pick Estuary for the default Kodi Interface

Many thanks for your helpful reply. I had only just posted this when I thought that I should first have googled it. I had completely forgotten that I needed to select System since not all options are available in the sub menus.

Thanks again