Eeew, yeah, that's patronizing -- and it’s even worse if he treats your colleagues differently. I suggest tackling this with two approaches.
First, when he claims, "Oh, I thought you said X" despite you clearly stating Y, treat it as a communication issue that needs resolution. Either he genuinely misinterprets your directions, in which case you need to identify the root of the confusion (perhaps he's not reading carefully, or maybe your instructions aren't as clear as you think), or he’s simply making excuses to cover up his mistakes, which you should point out so that he understands it’s reflecting poorly on him. Next time it happens, say, “Hmmm, what made you think I'd said X? I believe I'd mentioned Y, so let’s pull up the email and see where the miscommunication occurred.” This wouldn’t be appropriate if it happened only once, but given the pattern, it’s important to determine why this keeps happening. If he agrees that your email is clear, he might realize his error. If it happens again, say, “This has come up several times now, and it seems you need a better system for capturing instructions from emails.”
Second, address the condescending "good job" comments. If it were an isolated incident, letting it go might be okay, but a recurring pattern needs addressing. He should understand that such remarks can be perceived as patronizing, and if rooted in sexism, he’ll need to address this early in his career. Sometimes, displaying a natural emotional reaction, like a confused frown followed by a pause, can send a subtle message. However, if that doesn’t work, you need to be direct: “When someone points out an error in your work, it’s best to respond by acknowledging it or asking clarifying questions if needed. Responding with ‘good job’ can seem patronizing, and I’m sure that’s not your intent. Although minor, it impacts how you are perceived.”
If he seems open to feedback and shows potential in other areas, you could add, “It seems you feel the need to save face when errors are pointed out. In a professional setting, acknowledging the mistake and correcting it is more effective. This might be something you didn’t learn in school but is crucial at work.” Given his overall poor performance, however, it’s likely best to focus primarily on improving his work quality before delving into more nuanced feedback.
It’s essential to address these issues because they affect your effectiveness as a manager and will benefit you professionally in the long run. Do so matter-of-factly, without turning it into a lecture, but ensure it’s addressed.