When you take a screenshot on Mac OS, the default system will create a picture with name as “Screen Shot xxx” saved on Desktop under file format as “.png”.
If you want to change the file format, location or name of this file, you need to use Terminal apps (in Application) to change the defaults of Apple system.
After opening Terminal, for each need, you can simply use the following commands:
1. Changing file format of the screenshot picture:
defaults write com.apple.screencapture type jpg; killall SystemUIServer
2. Changing file name of the screenshot picture:
defaults write com.apple.screencapture name "Screen Shot"; killall SystemUIServer
3. Changing file location for the screenshot picture:
defaults write com.apple.screencapture location "/Users/YourUserName/Desktop"
On above command, change YourUserName to your user name if you want to save files on Desktop.
It’s done. Good luck and have fun.