I have a white DBS LiveFresh Credit Card (Student) & also a black DBS Visa Debit Card. I'm just confused between the two, which should I use for paying things to receive the most cashback?

I've graduated recently, found a job & started on my little personal finance journey. I hv a Multiplier acct, so I know to hit 1 of e criteria, its min $1 spend on credit card. But sometimes when i go for meals/restaurants I dont know which card to use to get e most cashback. This is assuming i have sufficient funds in my acct and i dont really need to 'pay for stuff by credit' (cuz mum say thats borrowing from banks, nt gd)

PS: recently trying to pay for stuff via Grabpay to receive points too