By default all blogger template is design in a way that H1 tag is given to homepage title, H2 is for blog description or date header, sidebar header, H3 is for post title. Heading tags range from H1 to H6 in descending order of importance.
Headlines, bolded and highlighted text are first taken into consideration by search engines. Blog title is the most important part of a blog which is assigned with H1 tag, followed by post title, but assigned with H3 tag which it should be given H2 tag, because your post title is what that drag the attention of your readers even in search engine listing. So if you want to tell the search robots how important is your post title and if you want better placement for your blog in search engine listing, you will have to change to post title tag from H3 to H2. follow the instructions below on how to change your post title tag.
How To Change Your Post Title Headings
Replace it with the code below
But if you can't find the first code, then find and replace all occurrence of <h3 with <h2, and all occurrence of </h3> with </h2>.