The tags will will give your blog template optimization also many times the tags are taking in main role in getting traffic. Many blogger i think so all blogger templates are default design such that the H1 tag give you the Homepage main title and H2 give you your blog description or Header dates, sidebar headers and H3 is assigned for post titles.
Now a days all post title tags are much more important than other tags of your Blog. Now a days if you are using your post tiles with H1 tag i think so you can get more traffic.
Your blogger post titles that give to search engines like Google or any search engines an update and are indexed and crawled by search engine robots. In SEO the post title is referred as the King whiles post content is referred as the Queen. So if the king is treated with H3 tag instead of H2 tag then I guess you must re-plan your Traffic campaign.
Changing your Post title Heading tag
First login to your blogger dashboard.
Go to Blogger design-Edit HTML
Download or backup your template.
Search for this by using (Ctrl + F)
Then search for
Save your template.
See your Blog and congratulations with new look!