How to change created date for backlog items?

[rashid asgari]

Hey everyone, I was wondering if there is a way to change the added date for backlog items. What i want to achieve is that i wanna populate my backlog with past sprint items and have their burn downs. But when i add all the items and tasks and then assign them To-Do and Effort hours and then i close them on the same day the whole graph looks like a single point! I would really appreciate it if anyone could help me out, this is kinda urgent.