ExifToolGUI 5.16 question about editing data in Workspace

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I just found the ExifToolGUI 5.16 (no longer supported but someone made a new one), and was wondering how to edit text, such as text in the IPTC and XMP files as well as DateTimeOriginal field in Workspace?

I typed some text in the box at the bottom of the Workspace panel, but the Save button is grayed out.

What am I doing wrong, or can't data be changed using ExifToolGUI?

Thanks

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I found the answer. I need to hit the Enter key, then the Save button is clickable.