Take credit for your ideas, professional boundaries and utter lack of respect

Well, it’s really not about “putting them in their place.” That kind of thinking isn’t going to lead you in a direction that will command respect. It’s about earning respect by acting in a way that warrants respect: doing excellent work, conducting yourself professionally and maintaining professional boundaries, and approaching everyone with respect and dignity. So if they start talking about their relationships, you say, “We should turn this back to work” (after first talking to them a minute or two, because that’s normal politeness and managers aren’t required to instantly shut down all non-work conversation). If they take credit for your ideas, you correct the record with your own boss (calmly and matter-of-factly, not defensively) — if indeed it was really credit-stealing and not just “hey, we’re going to do X now.” If they ask you to hang out outside of work, you decline. And you manage: You set clear expectations, give useful feedback, warn people when they’re falling short of what you need, and set and enforce consequences when people fall short of your expectations. You can’t force respect out of people. You’ve got to earn it. (That said, if people are behaving disrespectfully, you absolutely can take that on directly, make it clear what is and isn’t acceptable, and then hold people accountable to that standard. But it’s going to be a lot more effective if it’s backed up in all the ways above.)
When people do something blatantly disrespectful, I am speechless. That's a problem.