can someone help me?

Please answer the question in the space indicated below. "I took some accounting but I never really understood the debits and credits. For instance, I remember my teacher saying that debits increase cash and credits decrease cash. That doesn't make sense to me, since when I use my debit card to purchase something, my cash is going down, not up, and it shows as a debit on my bank statement. Also, when I deposit money into my bank account, it shows my account being credited. Why is it backwards? I am so confused so thanks for helping me