[Plugin: W3 Total Cache] Creating new site and making changes to .htaccess

I create sub-sites from my main wordpress, the site gets created but total cache says “Enhanced mode page cache is not operational. Your .htaccess rules could not be modified.” I see where I can manually add the changes to .htaccess which is currently set @ 644 do I change permissions and if so to what?

Or how do I fix? I only want to be careful not to set the wrong permission if this is the case.