Within the Penta WebApp in the menu item "My card" you can change the PIN yourself. 

It is important that the Penta app is paired with your device so that you can perform the setup.

If you have any further questions, Penta customer service will be happy to help you from 9:00 a.m. to 6:00 p.m. weekdays by phone at +49 30 255 585 803 or by email at help@getpenta.com