Asalamo aleikoum wa rahmatulah. If a person wants to ask forgivness to his parents for any disrespectdul act he may have done towards them can he do this in a general manner for example saying: Mum can you forgive me anytime I made you angry or I may have done uqoq to you? .If she accepts and say yes, will Allah accept this even if she does not remember certain things when she said yes?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

Requesting forgiveness from one's parents using the same wording mentioned in the question will benefit him. It is good for a person to ask forgiveness from his parents especially that their right is great and it is one of the most emphatic rights [that a person is required to fulfill].

Allah knows best.