So you know why changing blog title is necessary that's why you are reading this right? if not then changing blog title is another factor which will help you in search engine optimization. let's find out how to change blog title:-
your blog title will look like this in any search engines
As you can see that it is showing (SEO FOR BLOG:HOW TO ADD META TAGS IN BLOG FOR BETTER SEO)
to change this
FIRST: go to DESIGN>EDIT HTML and find this line
<title><data:blog.pageTitle/></title>
After finding this line just replace it with this
<b:if cond='data:blog.pageType == "index"'>
<title><data:blog.title/></title>
<b:else/>
<title><data:blog.pageName/></title>
</b:if>
<title><data:blog.title/></title>
<b:else/>
<title><data:blog.pageName/></title>
</b:if>
So here it is as you can see my blog title has been changed.
save your template and you are done