In the titles section of the settings, I have added %%excerpt%% to the description box for posts. However, when I view the source code of the posts on my site, they are showing the meta description with the first bit of content on the site, not the excerpts I have written.
I use a W3 cache, and have purged the cache, but its still the first bit of content on the page that is being used, not the excerpts.