Just realized you are stuck on credit purchase vs credit on statements. These are two diff things.

When you buy sth on credit this happens.
Supply Increases (literally)>>>crediting here means you're assigning a positive value monetary wise to that account. (you could technically sell the supply to generate cash)
Your Debt increases: Debit Account Payable because now you have a negative value on this account. (your went from 0 to -100 to pay that later)

2nd transcation.
you pay 100

now
you have to cancel that debt (not debit) increase by paying the due amount.

Bank account gets debited (reduce the cash on that account so debit)
Account payable gets Credited (you are paying money to bring the account from -100 to 0 now, this is increase in account value cash wise) so we credit 100.

If you look at these both transactions at the end:

you can see
you credited Supply AC
you debited your back account (This would be a straight transaction if you paid cash right away)

you brought ac payble from 0-100 on first transcation; then on the second paid +100 to bring back to 0.(cancelled that prev transcation)