Google keep changing some of my titles

Google keeps changing how some of my titles show in the serps and It keeps adding my blog name next to titles which are short.
For example I have a title "World's best widgets for 2015 - Blue lovers take a look" and it changes it to "Best Widgets - BlogName"
I use Yoast and most of my titles are as they are supposed to be except for the part that google adds my blogname when my title has space for it.
Is there something i can do? It is annoying

How are you settings? probably you have postname + blogname
are you using another plugin like all in one seo pack?

araqueli said:

How are you settings? probably you have postname + blogname
are you using another plugin like all in one seo pack?

Click to expand...

No I am not using another plugin for seo and I manually insert my titles in the SEO title option. I have also disabled "force rewrite titles".
Maybe that's the reason? What force rewrite titles do? Do I need to enable this?

Force rewrite titles it to change the titles of your previous posts if you make a change in the settings. You use it when you want to make a bulk change to all the post you already made.

And google is known to make changes to titles and descriptions in serps so maybe it changes it to something it favors?