Credibility includes admitting when memory is uncertain.

Nobody’s recollection is exact, and pretending otherwise is a small dishonesty that eventually surfaces. Saying that you are fairly sure but not certain, or that you may be misremembering the detail, does not weaken your account. It tells people you distinguish between what you recall and what happened, which is precisely why the rest of your account can be trusted.

When recounting something, mark the parts that are hazy. Especially in a dispute, where the temptation to firm up the memory is strongest. Admitted uncertainty is what makes claimed certainty mean something.