Hi @ghina.altal, it seems like your main WordPress site works properly in HTTPS now.
However, you mention this:
seems that is mixed content after adding "s" to the site URL and home URL dashbored
It seems like the main site works properly, without mixed content warnings. However we can't check wp-admin. Could it be possible you have enabled a custom theme for wp-admin? If so could you switch back to the default/
If not, please check in the browser console (right click -> Inspect element -> Network tab and then reload/refresh page), and let us know which assets are getting loaded via HTTP in case there's anything we can do about it.