Its not so much a matter of knowing what the buttons do, its that their functions change according to what mode the scope's in and what other selections are active.
That's why its a pity that its no longer economically viable for novices to learn on a real CRT pure analog scope. You wouldn't be confused for long by input coupling if it was a physical three position lever switch AC-Gnd-DC right next to the input BNC, and if you were used to having to ground the input and tweak the Y shift to zero the trace to whichever graticule line was convenient for the waveform you were viewing. You'd also probably get to meet the joys of 'Pull x10' on the Y variable gain knob which would sum in an AC coupled x9 amplified signal to give a DC gain of x1 and an AC gain of x10, letting you look at noise/ripple on power rails or other slowly varying or DC signals without them shooting off the screen.
However a new analog scope with reasonable performance costs the same or more than an entry level digital scope, and I wouldn't wish an chronically unreliable crusty old boatanchor on an absolute novice, even at under $50.
My first scope was all valve: Hartley Electromotive Type 13A Oscilloscope, just like this one, except mine was less beat up and had its original CRT hood and a graticule.
It was a reliable dual beam boatanchor, but had rather limited bandwidth and a piss poor trigger. It taught me a lot and I even used it for figuring out serial keyboard protocols and the like.