The search results including those on search engines like Google and Yahoo use these titles.So it is always better to keep your title more related to your post content.
Search Engines do not re-index your site every day. So these changes won’t be reflected onto Google Search result pages until Google’s crawlers reach that page again. 

Login to your blogger account
From your Dashboard opt for Layout/ Design/Template
Now choose Edit Html. You will see your template code there. In that template code find.

Blog Title - Post Title

<title><data:blog.pageTitle/></title>

and replace it with

Post Title - Blog Title

<b:if cond='data:blog.url == data:blog.homepageUrl'>
<title><data:blog.pageTitle/></title>
<b:else/>
<title><data:blog.pageName/><b:if cond='data:blog.pageName'> - </b:if><data:blog.title/></title>
</b:if>