Cannot be done on mobile app. Can do it at browser internet banking.i found out the alert for UOB one is at $500 and above transaction.
to set alert for lower sum, i have to obtain the forms at the branch and write in..
Left panel, select Account Services --> Manage alerts. Then select Credit/Cashplus/Debit Card.
Change amounts to 0.01.
While you are at this, go through everything and set your alerts for everything - ATM, fund transfers etc.

