Go to sbb-tickets.cc
There you will see all options, including those without changes.
Normal tickets are for a route, not a specific train. So you can just take any train on the route, wether direct or with a change. A supsersaver ticket is cheaper, but for a specific train. A saver day pass is often cheaper as well, and allows you to take all public transport in the country. Buy what suits you.
Tickets do not come with a seat reservation, but you do not need those.