Notes on spreadsheet have all changed

Hi. 

I have a spreadsheet that heavily uses notes (formerly comments) to comment on the data. At some stage in the past 3 months all the notes have changed  to include the following at the start of each note:

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ID#AAAAD-NYSMg
tc={3601F7CA-C9E9-42F1-929B-4F5ACFBAC8A8} (2019-12-01 23:06:40)
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Comment:

I assume this was caused due to a newer version of excel being used to open the document which is stored on dropbox. 

How do I change the comments back to the  way they were without all the extra info at the start? and how do I keep it that way? There are hundreds of comments with this issue so it would take days to change them all manually. And the ones I have tried to edit to remove the extra text have reverted back when the document is opened on someone elses computer. 

Thanks for the help