How to reassign reviewer?

Hello my name is Ruben from Indonesia, currently I am working in one of the private university in Indonesia. And I am working for the administration journal website from my major that I am working with right now. I open the this OJS through website (not through software), I hope I could get some help from here, here is my problem, once I assigned an article to ask the review from my reviewer list, then the reviewer decline to review, but then the reviewer agreed to review if we prolong the due date, the problem is I couldnt assign to that particular reviewer because that reviewer has already declined to review, how we solve this problem to let the system could be able assign to this reviewer. I am wishing for the help. Thank you very much.