直接说：Can you change a problem?
委婉一点，客气一点：Could you change a problem?

Can you change another the subject ?

You can do another problem

next……
hahaha

过！

Can you change another subject/topic/question？
另外老外一般不用problem
如果是problem 就是很严重 严肃的问题
一般问题 用 question
Can I ask a question？ 不说 problem

Could you change the subject?

Can you give me another question?