Is it a sin to disobey the advice of your confessor?
Do Confessors have jurisdiction from the Church to order you outside of your assigned penance? (I think there are some spiritual directors who have that power)
How can you tell the difference between advice and command in confession if such a distinction exists?
What happens(what is your status) if you remember sins during absolution?
If you are not sure something is a grave sin and you do it anyway does that make that sin a grave matter?
It depends. For example, if the priest in the confessional advises you not to steal, then it would be a sin to ignore the advice. If he advises you to eat bananas, it would not be a sin to ignore the advice.
If you remember something during absolution just say “Father, I remembered something” or words similar to that. If you don’t want to interrupt him while he is giving absolution wait until he is done, then say Father, I remembered something and go from there.
If you’re not sure don’t do it until you are sure.
I recommend a book that I am reading right now by Scott Hann called “Lord, Have Mercy - The Healing Power of Confession”, it has been very educational and enlightening.
Unless you know for certain that a particular priest is wrong about a moral issue, it’s best to follow his advice given in confession.
Sin which is uncertain is not mortal.
It’s possible but not likely that one would forget to mention a mortal sin; mortal sins are the big ones which stand out in your mind–grave matter with full reflection and consent. If you really forgot a mortal sin and remember it during absolution, just mention it right away, or in the next confessin.
A venial sin which is forgotten does not need to be mentioned.
If you find yourself obsessing about the details of confession, it’s likely that you are being scrupulous.
A mortal sin is always a grave matter; however, a grave matter isn’t always a mortal sin. Two other conditions need to be present. Sufficient reflection and full concent of the will.