Do junior developers these day memorize code or coding flow, logic, pattern?

I am new to web development. After attemping to code or build something with my own ideas, I have found out that I am not capable enough to build a real-world useful websites or web applications. I know syntaxes, how some built-in functions work, how oop works, how html, css, javascript, work but mostly just fundamental things. When I look up youtube, I see people teach how to build e-commerce websites, web applications... it's just the ways they teach are write this or that, put it here, move this to there... with little or none detailed explaination. No matter what kind of programming , desktop application, mobile, web...there are always those libraries and framework which are extremely complex to understand... I almost give up sometimes then I think I must have a proper job. So, I keep dealing with this unclear thought and feeling... Can senior developers and talented people here give me some advice to a beginner like me??? My question is Do I need to remember how to build those websites or web app forever???