One post front/multiple in archives

I’m working on https://wcrf.us/. I’d like only one post to show on the front page there (as it is right now). However, in the category page (https://wcrf.us/index.php?cat=1) or search page (https://wcrf.us/index.php?s=update) I’d like it to show 3 or 5 posts. Does anyone know of a way I can get this to work? Thanks!