The default 1st day of the week is set on your iPhone and is based on your region. To change this follow these steps:
Go to your Settings app on your iPhone
Tap 'General'
Scroll down and tap 'Language & Region'
Scroll down and tap 'First Day of Week'
Select your preferred first day of the week
Now close and reopen Cupla and you will see the first day of the week has changed
On Android: Cupla follows your phone's language and region. On Android 14 and later you can choose a different first day for your whole phone: open Settings and search for First day of week (on many phones it's under System → Languages → Regional preferences). Choose your day, then close Cupla from your recent apps and open it again. The first-day setting inside a calendar app, such as Samsung Calendar or Google Calendar, changes only that app.
