I have a little bit confused on these statements.
As we know, we should say you are. But,how about your ?
Should we use is or are ?
Example
What is your problem or what are your problem ?
Where is your homework or where are your homework?
Or both also can be used in this case ?
"You are" is not the same as "your"
The verb should agree with the subject, and when the subject is "you" the verb (to be) becomes "are"
However in your example, the question
What is your problem?
Is formed from the statement:
Your problem is ...
The subject here is "Your problem" and that is singular. The word "Your" acts to modify the word problem, but it doesn't change it to plural. The verb agrees with the singular "problem" *"What are your problem" is absolutely wrong.
However if you have "problems" you would use "are"
Problems are...
Your problems are ...
What are your problems?
Exactly the same rule applies to "homework" which is singular.
