So its not expected to remember everything 100% off the top of your head. The level of understanding you want at least is being able to identify and re-lookup a given topic. So for example, you don’t remember exactly how a radio button works, but you know about what a radio button is. This is the only knowledge you need to go learn more. Looking up references like on mdn gives you tons of easy knowledge without remembering more than “I need a radio button”. You can apply this sort of thinking to almost anything up to a point.
You will find as you go further and learn more than you can’t look everything up (you can try hehe) as it will take to long, or what you find isn’t 100% what you need. This is where experience comes in. For example if you tried to lookup a way to get multiple options to be checked using a radio button in your references you’d be more or less wasting your time as thats more of a checkbox feature. You wouldn’t of known this without having some experience on the differences.
Furthermore once you start getting deeper in programming specifically, there will be problems that are so open ended you will end up sitting around going “what do I do!” and thats ok that just means you need more experience around these problems so they are more familiar.
Don’t be afraid of not knowing, embrace it as its a sign there is more to learn and room to grow. Acknowledge you don’t need to know everything, but you do need to be able to learn (almost) anything over time.
Experience is experience, and such comes with time. Keep at it and good luck!