There should be some new O-rings for those couplings and they should be lubed. If it was me, I'd put a dab of silicon lubricant on the threads as well, just to make it easier to turn. And I don;t think they need to be much more than hand-tight. It's compressing the O-ring that seals it.
The big waist O-ring? I'd take a peek at it and see if it's already greasy. And also make sure that nobody forgot anything inside, like the air bleed screen, or to tighten the wing nut.