Good audience retention is one of the hardest things to succeed with as a YouTuber. But you can start with yourself, you most likely have been watching a lot of other peoples videos throughout the years. Some videos you start watching but leave before they are over. Other videos you skip around, you watch for a while, jump forward, watch for a while, jump forward. And a few videos you watch all the way from the start to the end. What is the reason that you stop watching some videos early? What are the reason that you are skipping stuff jumping forward in some videos? And what was the reason that you watched from start to end in a video? Try to think and come up with reasons and then apply does reasons to your own videos.
Here are some reasons that can make myself stop watching videos early or jump forward in them:
Bad audio quality.
Bad video quality.
I find the voice annoying to listen to.
If it's hard to hear what the person is saying (mumbling etc).
If the person speaks in a foreign language and is really bad at pronouncing words.
If the person speaks with a accent that makes it hard for me to understand or just sounds annoying to me.
The video was not what I expected (got fooled by title/thumbnail).
It was a miss click, I didn't intend to watch that video.
Ads during the video.
Bad storytelling.
Getting of topic (for a few curtain individual that are really funny or great at storytelling getting off topic can be great but for most people it's not).
Spending 2 min to say something that could be said in 10 seconds.
Boring (what's boring depends on topic, for a vlog it could be personality or humor for an instruction video it could be a slow monotone voice).
Prolonging the video to reach a curtain timer. If you have content for 4 min but try to make a 10 min video 6 min of that video will most likely suck just make it a 4 min video.
Intros, if the are longer than 2-3 seconds I always skip them.
Taking to much time before starting the actual video. Some people talk for like 30-80 seconds before the video actually start. There is a reason people post timers in the comments like "skip to 1:36".