The first two are the advert
In search results Apple shows the first two or three screenshots inline, and a large share of visitors decide from that alone without ever opening the product page. Whatever your app is for has to be legible there.
That means the first screenshot is not a screenshot. It is a poster: one clear promise in large type over a simplified version of your interface. A raw capture of a busy screen is unreadable at that size and says nothing.
Design the first two for a thumbnail in a list, not for a phone held in your hand.
One idea per screenshot
Each panel should make exactly one point, with a short caption that could be read at arm's length. Three features crammed into one image means none of them register.
Order them by what a stranger needs to believe, in order: what it does, why it is better, then the details. The sequence is an argument, not a tour of your tabs.
Caption in words, not feature names
"Split the bill in two taps" is a caption. "Advanced bill splitting engine" is a feature name and it persuades nobody.
Write what the person gets. Short enough to read in the time it takes to scroll past, which is about a second.
Use the app preview video carefully
An app preview video autoplays in the first slot on the product page, which means it replaces your strongest still image for anyone who lands there. That is worth it when the app is genuinely better in motion, such as a game or a drawing tool, and a loss when it is not.
If you ship one, make the first frame work as a still, because that is what shows before it plays and in every context that does not autoplay.