this is the correct way to form the sentence in a easy meaningful way . because when we say " اضغط مطوّلًا للانتقال إلى البداية. " as in the sentence which is already applied , that means : press and hold from up ! to jump to the start ! . Which doesn't make sense at all .

That's absolutely a wrong and aggressive way to explain my translation. You, me and all of us know that you explained it very wrong.
Both of "مطوّلا" and "باستمرار" are correct in this sentence.
The reason that I didn't use "باستمرار" because it in some way has the meaning of "many clicks" and not a "long press".

I believe that " مطولا" give the most correct meaning.

that's my point Sir, and I really didn't like your aggressive way when you said " which doesn't make sense at all" while it's really makeing sense:).

Probably a better translation