DH just got a new vehicle and we are installing DDs Britax Boulevard RF using the latch. I'm having trouble loosening and tightening the latch buckles to get a secure install. Is there a trick to doing this? Do I need to push the grey button on top of the buckle? I just can't seem to loosen and tighten the buckles on the latch connectors I can't seem to find instructions either. . .