In your HubSpot account, click the settings icon, in the main navigation bar.

On the left sidebar menu, navigate to Website > Blog

Select the blog that you want to update on the Current view dropdown:

Once you selected the desired template, navigate to the Templates tab to update the templates on the blog pages.
Click the Actions dropdown to change the template for the Blog post and Blog Listing pages.

After you update the templates, don’t forget to hit Save.
Reference video: https://share.vidyard.com/watch/3TighzoNgNBU7LHXhnVa1J?