Please note that you could find your new IBAN details by logging into your personal page at mypos.com >> menu Merchant account >> Accounts >> clicking on the particular account on your right >> and on your right again you should be able to see a tab Details including your IBAN; BIC; Account number and a tab Download. This way you could quickly download a file containing all necessary information.
In addition please also note that you could find your new IBAN details by logging in your myPOS mobile app as well >> More>> Merchant account >> Accounts >> clicking on the EUR flag.