Hi @hammad98 !
Congrats and welcome to the club 
That’s normal and will continue to happen as you learn how to code.
Remember this is all new to you. So you aren’t expected to remember or get everything the first time through.
What is happening here is what happens to thousands of people trying to learn how to code.
When you are introduced to something new, it will take tons of practice for it to stick and make sense.
That is like if I tried to teach you how to cook a recipe for the first time and expected you to replicate from memory perfectly and not mess up. You only learned it once. You will need to make the dish multiple times for it to start feeling comfortable.
Same goes for any skill like learning a musical instrument, learning a foreign language or learning programming.
For the labs, take it slow and take it one user story at a time. If you forget something review the lectures, google it or ask questions for help.
Then once you complete the lab, you will move to the next one and there will be more struggles. That is where you repeat the process with learning and getting better.
That is programming. It will takes tons of practice and time before you get comfortable with most of this.
Hope that helps