Easy ones first, always
The first two questions should be the ones almost everyone gets right. Not to flatter: someone who's already got two right will reach the end even when it gets harder, while someone who fails immediately has a reason to close and none to stay.
The corollary is that the hardest question never goes last. The last one should be answerable, so the final thing the person feels is having finished rather than having given up.
One question per screen changes the outcome
A quiz on a single page shows its length immediately, and length is the first thing that makes people leave. One question at a time hides it — not to deceive, but because the useful information is «how many are left», which a tick bar conveys better than a whole page to scroll.
Ten questions is the practical ceiling for a quiz opened on a phone in an idle moment. Beyond that you need strong motivation: a certificate, a shareable result, a training requirement.
Different results for different answers
The part that makes a quiz memorable is the ending, and it's also the one almost everyone gives up on. With conditional logic you can land on different endings — one message for people who answered one way, another for the rest — and that's the moment when the person is still looking at the screen.
Answer recall helps too: using the name given at the start in the final message costs one line and changes the tone of the whole quiz.
Automatic scoring matters less than you'd think
For a training or screening quiz at volume, a score computed by the form is convenient. For everything else — an entertainment quiz, a classroom check, a test with twenty people — exporting the CSV and counting with a formula is faster to set up and easier to review if someone disputes the result.
The rule: if the score decides something serious, it has to be re-checkable. A total computed inside the form and not re-examinable is convenient right up until the first dispute.
Easy ones first, one question per screen, and a different ending depending on the answers — that's the part people remember.