Problem with XPComment being filled with a default comment

[kodyman]

I'm a newbie to the workings of ExifTool and ExifToolGUI.  I've mostly used the GUI and since it's easier for me, not being well versed in scripting and command line.

I checked out ExifTool to see if it could help me in easily adding or editing notes to JPEG screenshots I take with a screenshot program.  I wasn't aware of all of the intricacies of metadata until I looked at it with ExifToolGUI. Still not sure if this is the best solution for my needs. Possibly someone has some suggestions.

Anyway, here is what I did leading up to my problem.
I have a test folder where I'm keeping the screenshots. One of the tests I did was right-click one of the JPEG images, then select Properties > Summary (Simple) and typed a test phrase ("This is a Test Phrase" for this example and without the quotes) in the Comments area. Selected Apply (maybe just OK, don't recall.)
I had already set up a Metadata Custom tab with various tags and the test phrase was displayed in the XPComment. Great.

Now the problem.
Whenever I take a new screenshot (each new screenshot is saved with a different file name) and right-click > Properties > Summary, the test phrase ("This is a Test Phrase" without the quotes) I used in the original test file above has been placed in the Comments of the new screenshot file. No matter how many new screenshots I take it's still there each time.

Searching the forum before posting this, I read a post saying that XPComment can do some screwy things at times. Looks like this may be one of them.
Are there any suggestions on how I can reset the XPComments so it will be empty for each new screenshot?

Thanks in advance!