What you’re looking for is how to be more tactful in your communication. And there’s probably a combination of learning how to let some things go without saying anything. Generally speaking, I don’t say anything at all unless someone asks me to. And some of this will just come with time and practice. But, since you’re looking for help today, there are plenty of resources here to help you. I recommend starting with Crucial Conversations: Tools for Talking When Stakes Are High, Second Edition (O’Neill Library: BF637.C45 C78 2012).