Imagine I've got a very important appointment today afternoon, the problem is that I am very sick and I would like to change the date of it
Shall I say : Would it better if we change the date or if we changed the date. Would, in that case, is a form of politeness in the present so I think present can do it , I can say if I'm not so polite Will it be better if we change the date.
If you are the one who is sick, it would be better to say
It would be better if we changed today's meeting
since you already know what you want to do and probably are not asking a question.
If you called to cancel, the conversations might go like this
You: I have to apologize, I am very sick today.
Them: Would it be better if we change the date?
You: Yes, I think it would be given my current state.
"Would it be" is the question form and "it would be" is the answer form of this idiom.
Eiher "change" or "changed" can be used in your context without lose of understanding.
I think it would be better if we change the date.
I think it would be better if we changed the date.
