For taking advantage of backdoor roth ira, do we have to open roth account every year? Same roth account can't be used?

In 2016 ,  i tried backdoor roth ira. so opened ira and then coverted to roth.

Now for 2017, i was told by broker that to take advantage of backdoor u can't use same roth ira account u have opened in 2016. You have to open new roth account for 2017.

How true is that?  how does this work?