By default, when a user clicks the site logo of a subsite, for example, then that user is redirected to that site’s home page. However, what if you want this link to redirect to the site collection home page?
I found a solution on the internet from this blog. Many thanks to the I Am Sam blog and specifically this post, which explains how to update the <SharePoint:SPSimpleSiteLink> element in your master page. This is a relatively painless workaround to a common request.
One item not mentioned in the post is the fact that, for subsites using the team site template, you need to ensure that the SharePoint Server Publishing feature is activated, as shown in the following screen shot: