How do I change the location of macOS screen captures?
According to this page...

defaults write com.apple.screencapture location &lt;path&gt;


Also, to turn on/off shadow:

defaults write com.apple.screencapture disable-shadow -bool true
defaults write com.apple.screencapture disable-shadow -bool false


And to change file type:

defaults write com.apple.screencapture type &lt;format&gt;


You'll want to

killall SystemUIServer


to make the commands take effect.