Bonjour
le passé composé avec "avoir"
The past participles with "avoir" NEVER agree with the subject.
They always are invariables
EXCEPT
when the direct object is before the verb, then the past participle will agree with it, even if it's a direct object pronoun.
But ONLY if the direct object is BEFORE the verb
example =
Ils ont mangé de la tarte. (the past participle doesn't agree)
La tarte qu'ils ont mangée -> the past participle agrees with "tarte" (fem. sing)
OR with a direct pronoun
Ils l'ont mangée --> agrees with l' ( = la tarte)
Another one
J'ai rencontré tes amis. (I met your friends)
Tes amis que j'ai rencontrés. (agree with the direct object "tes amis because it's before the verb)
OR
Je les ai rencontrés. (agree with "les" direct object pronoun")
Do you understand better ??? really hope this help ...
Ask me if you need any further explanations
☺☺☺