The other way is what some BIM Managers might do: it is to extract the Library Container File (LCF) into a folder on your hard drive.
Then you can open the GDL Objects and modify their default settings in the Library Editor Dialog. Then save them. When you modified all GDL Objects you wanted you can then recreated the LCF from the folder.
However, this is really BIM Manager level stuff. Also, GS states that the result of modifying the library is that the upgrader will not be able to upgrade it if a library hotfix comes out. So you either
1. Modify the LCF and not upgrade it with a library update if one comes out.
2. Use the modified LCF, but save a copy of the original LCF (which is always recommended before modifying), when the update comes out you switch back the original to its original location so the updater can find it and update it. Then you make those modifications again.
By the way there is a tool for converting Library Parts to XML and vice versa. It is in the PreviousLP_XMLConverter folder, complete with documentation, if you are serious about doing this. When the Library Parts are in XML, it is easy to modify certain values in the XML file which makes it easy to modify a lot of parameter values in many Library Parts in one step, as far as I know. Truth be told I never tried it so I don't know exactly how complicated it is.
But as always, save a backup before embarking on such an adventure.
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