Hello,
it seems that there are two versions of fonts.
The documents are using the different version of the same font than the one that you have installed on the system.
You would need to update the font as and when you will open the document and then save the documents.
Also try to restart the computer in safe boot so that the hidden caches for fonts could be cleared up
To start the MAC in safe boot hold the shift key down and then restart.
I hope this helps!