iPhone set to Gregorian calendar, however health app is Buddhist calendar
I do live in a buddhist country but set the phone up with a Gregorian calendar, however was just setting up some more details on the health app, and there is no way to change the Buddhist calendar. In Language and Region, its set up as greg cal, region being Thailand, date format is set at 19/08/2025, no Thai language has been added just English (UK), running iOS 18.5