[jiux]

Here's how to set screenshots to save in your Downloads folder:

defaults write com.apple.screencapture location ~/Downloads && killall SystemUIServer

[Delphiki]

Or press command+shift+5 click the "Options" button, and then the "Other Location..." option in the "Save to" menu, like it shows in the article.

[wintermutestwin]

TinkerTool lets you edit the Destination Folder, Format and some additional screenshot settings. I much prefer this because it allows me to quickly check the current setting as opposed to a "black box" CLI command.

[lloeki]

Maybe?

    defaults read com.apple.screencapture location