You already answered your question - use Property Manager.
If you have a draft file open you can go Properties > Property Manager.
That will show properties for the draft and the part or complete assembly structure.
Alternatively if you want to edit properties for a load of unrelated files (eg a set of draft files)
Just start Solid Edge but don't open a file.
Then from the application icon select Property manager.
From there you can select all the files you want to edit.
This is one reason why we keep all our draft files in a seperate folder.
bc.
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