Confusing meta descriptions/snippets

Hello everybody,

I would truly appreciate a critical feedback on my blog, InfographicsVillage.com

Again, I have some issues. I have installed Yoast SEO plugin but didn’t activate it and simply put a small meta description in the Header.php.

Just today while I was checking how my individual pages were ranking I found that many pages are ranking well there but not a single meta description is appearing correctly.

If a particular page is ranking, the meta description is showing is that of the home page and not a fragment of that certain post in the snippet section.

Again, sometimes the name of the other posts are appearing in the snippets.

Again, when I tried to search a single post by using the title in double quote, the home page ranked but not the individual page.

Yes, I searched using Google.

I’d really appreciate any helpful advice. Thanks in advance!!