@anneliesgeraets Hmmm. I wonder if it might help if you create an empty ‘practice’ site and walk through the steps there. Maybe it will be less confusing, and then, once you see how it works, you can do it again on your ‘real’ site.
I just created a test site and walked through the steps (to be sure I could explain them clearly), and it worked fine. Here’s the site I created as a test:
https://laborstreet.editorx.io/my-site
Here are the steps:
CHOOSE LANGUAGE PAGE
First, edit the default home page name to rename it to ‘Choose Language’. For clarity, add a title ‘Choose Language’ in the middle of the body. Remove the header from this page.
ENGLISH PAGES
Next, create a new page entitled ‘English One’. For clarity, put a title in the middle of the page body: ‘English One’.
Next, create another new page entitled ‘English Two’. For clarity, put a title in the middle of the page body: ‘English Two’.
Now, on the header for that page, edit the menu. First, rename the menu ‘English’. Next, add items – choose all the pages you’ve created so far.
SPANISH PAGES
Next, create a new page entitled ‘Spanish One’. For clarity, put a title in the middle of the page body: ‘Spanish One’.
Next, create another new page entitled ‘Spanish Two’. For clarity, put a title in the middle of the page body: ‘Spanish Two’.
NEW MENU
While you’re on the Spanish Two page, duplicate the header. This is going to be your Spanish header. On this new header, select the menu and click ‘Manage Menu’. Click the dropdown to select a menu and click ‘Manage Site Menus’. Now click ‘Add new menu’. Name the new menu Spanish.
Now, go back to manage menus, make sure the Spanish menu is selected, click ‘Add new item’ > ‘Site Pages’ and pick the two Spanish pages and the ‘Choose Language’ home page.
HEADERS
You now have two headers on this page, one with an English menu and another with a Spanish menu. Using the context menu, remove the English header from this page.
CHOOSING HEADERS
While you’re still on this page, click the ‘Masters’ icon in the toolbar to open up the sidebar listing of masters. Notice that one of the headers is checked – that’s the Spanish header. Click the three dots to get a menu and choose ‘Show on…’ Then pick the pages on which you want this menu displayed (Spanish One and Spanish Two).
Now go to the other header and click the three dots. This is your English header, so choose the English pages.
HOME PAGE CLEAN UP
Now go to the home page and add buttons for English and Spanish. They will link, respectively, to English One and Spanish One. This page shouldn’t use either header.
If you can make this work, you’ve mastered the process. If you have a problem, note specifically where it happens and let me know.