Be assertive enough to let them know how you feel, but say so in a nice way. They will appreciate your honesty a lot more.
Keep your relationship private. It’s very easy to unintentionally involve your in-laws in your private matters.
Set appointments with your in-laws. If you schedule time to see your in-laws, they’ll be less likely to pop over unannounced.
It is necessary to set boundaries with in-laws. When you do so, speak to them in a respectful way so they don’t feel like they are being rejected or scolded.
Your spouse needs to know how you feel. Sure your in-laws are a pain, but remember, they’re still your spouse’s parents. Agree on how to deal with them and remember to stay consistent.
Be polite without being fake. It’s good to say things like “please” and “thank you” and offer to help when you can. Be cordial, but don’t go overboard with flattery.