You should be receiving a One Time Password (OTP) on your registered mobile phone.
Press and 
until you see a dash on the screen.
On the Secure Device, enter the 6-digit OTP then press the again.
A new 6-digit secure PIN will then be generated.
Enter the 6-digit secure PIN in DBS iBanking where SMS OTP and Secure Device authentication are required.
Then, follow the on screen instructions to complete the transaction.