Changes are being marked on linked excel file

[Megan]

I have a PowerPoint presentation with several linked files. One of the links
in the powerpoint presentation appears to show tracked changes when the
linked file is updated (it shows a blue line on the left similar to tracked
changes in Word 2000). I can't get the blue line to go away - any ideas?
View-Markup does not appear to be an option as it is greyed out on my menu.

Thanks in advance for your help!
M.

 

[Megan]

They are linked excel files. I had gone in to try to turn off any tracked
changes, but the workbook was not set to share.