Hello,
I use yoo-phoenix template.
and Joomsef 3.9.5
Configuration :
Title and meta tags :
Metada auto-generation : Always
Prefer joomsef titles : yes
Use sitename in page titles : no

But on each page on my site, it's the sitename that appears in first in the title. Il don't want it, only for the homepage.
How change that ?
See my site : www.aseptair.fr

Thank you for your replies

Hi,
Make sure that Enable Meta Tags management is also set to Yes and that everything is listed as Enabled in JoomSEF's Control panel in the SEF Status box.
Try also clearing JoomSEF and Joomla caches.

I've tried setting your sitename on my test server and the configuration works correctly, so if none of the above helps, there's probably either the template or some other plugin installed that interferes with JoomSEF functionality.