boskostupar It is already activated, otherwise the “gauge” in your screenshot wouldn’t show up.
As with SBB.ch or other webshops, there’s no default payment option. Usually, the “default“ behavior is that the payment option used with your last order keeps being used with every new order, unless you change it.
So actually your question is: How do change the payment option in the app when buying a ticket?
Answer: In the last “checkout” step of the ticket purchase process, tap the icon looking like your current credit card just on the left of the big red “buy ticket…” button and select Halbtax Plus.
Same for EasyRide, which has a separate icon/setting.
