Archive page – want to change format

Hello

I am using the ‘Adamos’ theme and the archive file it comes with shows the whole content of the post.

I just want an excerpt of the post to show, but part of a two column format. The only way I seem to be able to get more than one post to show on the page is by limiting the number of posts. However when I do that the navigation stops working and just keep showing same posts from first page on all other pages.

Any ideas?

thanks in advance