Hello Heayangoox13
Do you want to take an earlier train for personal reasons or was this change of timetable announced by SBB?
In the first case, what kind of ticket so you have? With a point-to-point ticket or a Saver Day Pass you can take an earlier train with the same ticket.
With a Supersaver Ticket it is not allowed. You must buy a new ticket a get a refund of the Supersaver Ticket with a fee of 10 CHF. Call the Contact Center of the SBB with this number or visit a ticket office in Switzerland:
0848 44 66 88
(24/7, waiting times may occur)
From a foreign country the number is: +41 51 225 78 56
Kind Regards
Danhiel