It's probably there for those who used to "page"by (no login)
Way back before emulators scrolled the text used to keep on writing over itself. At a strategic point you had to press the page key (which had a similar effect to CLS). I guess the scroll lock was introduced for those of us who thought scrolling was a new fangled gimmick that would soon be forgotten.
Newbies usually go to www.qbasic.com and click on
The QBasic Forum
Forum regulars have their own ways, which include The QBasic Community Forums