I note that the file is a .png file.  This was taken with the new laptop.  How do I tell it that I want a .jpeg file?
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What you’re really asking is: How can I set the default format for screenshots I take on my mac to be jpegs? By default, the mac wants to use png as the standard for screenshots so you’ll need to go in to terminal to change this.

First, using spotlight, open terminal.
Next, type (or copy and paste) the following line of code: defaults write com.apple.screencapture type jpg
Now log out of your user and back in again for the change to take effect or you could type: killall SystemUIServer into terminal and hit return.

You’ve now set your mac to take screenshots in the form of jpegs.