I would like show categories on the left instead of clicking the "Explore" first and then choosing a category. In other words, I would like viewers to be able to choose a category at first visit. Is it possible to do it? Thanks.
Not possible to do with the current system settings and to achieve this you need to store the user preference in the DB. Chevereto doesn't provide a plugin API yet so I strongly discourage to try to add this on your own to the system.