Hello!! For short distance, less than 2 hours, do we need to buy our tickets in advance ? Thank you for your help.
You do not need to buy any tickets in advance.
No need nor real advantage buying public transport tickets ahead of time for trips in Switzerland. Outside some "super saver tickets" regular ticket prices do not change.
Seat reservation is a different issue - not a question of "short distance". For a very few tourist trains and many international trains seat reservation is required. For part of the trains in Switzerland seat reservation is possible, but seldom done. For most trains seat reservation is not possible - ticket or pass holders board train, regular tickets are usually valid for any train during the day they are valid.
Have a look at TA Switzerland forum "Top questions ..." - https://www.tripadvisor.com/ShowForum-g18804…
Zekeeva just a tip, your post is not connected to the the original question i would suggest you re-post as a new question and you may get answers to your question.