Widget fonts change when log out of site

Hi
I have recently used WP google fonts to change fonts for all main body text. When I am logged into my site the font for my sidebar widgets are the same as the rest of the site. When I log out, and view my site as a visitor, on my home page, the widget fonts change to a different font…I am using Open Sans, it seems to revert to another type within sans-serif family when logged out I am summising.
Why would this be? I have tried everything with the somewhat limited knowledge I have.
Is there css code I can put in to stop this from happening?
Thank you very much.
Daniella.