Label Text Change on Every Button Click

I want to change my label on button click, say i have 5 questions, which i need to display on every button "Next" click.
I have tried this, but on every click, it displays the first one("xxxxxx") only.

int i = 0;    
string[] Question = { "xxxxxx", "yyyy", "zzzz" , "ddddddd" , "dddcc" };            
Changetext.Text = Question[i];
i++;