I learned that ofter the word "que" you should use the subjective. I am confused about the correct grammar here. I want to say to an older person "I am happy to know you liked them." "them" refers to a gift and it is plural.
For now I have:
Que alegira me da sabre que le gustaron.
Is this correct? Is so, the verb "gustar" is in agreement with which subject? How can I write this with "vos" or is vos les formal than "usted"?