Cred (believe)
Cred
Latin credere: to believe, to trust.
Is Sana's story about a talking parrot credible, or just made up?
Incredible
So amazing it is hard to believe.
The view from the hill in Munnar was incredible.
Credit
Trust that you will pay later; also praise for something done.
The team gave Rohan credit for the winning idea.
Remember: Cred = believe: a credit card trusts you to pay; credentials make people believe you. Incredible ends in -ible, not -able.