I changed the eMail-adress for my apple-ID but now I cannot change my Apple-ID on my macbook.

Hey there,

I am new on apple MacBooks and have got a bit more trouble than I expected if I am being honest.
First of all I hate having several different passwords and not being able to use one again, that has been used before. That is definitely not helping.
Because of that - and because I changed my email-address - I also changed my Apple-ID. But now I seem not to be able to change my apple-ID on my macbook, so a lot of the things do not work anymore.
Where can I change the Apple-ID on my laptop? Like "now user "apple-ID X" uses the macbook" instead of "user Y".

I am sorry but I don't know how else I could explain it.

Would be really thankful if you could help me!

Thank you very much!