Library objects allow you to place unique instances of that object based on the settings of the parameters.
They will not be linked in anyway, so as Karl mentioned you will need to select all the objects you want to modify and change the parameter for all of them at the same time (rather than individually).
If you want copies that do all change when you alter a 'master' element then you will want to look into 'Hotlinked Modules'.
This could be a single object or a group of any elements that can be saved as a module.
Then instances of that module are placed.
When ever you edit the master module you then have the option to update the placed instances to match (or not).
This is not what I would do for placing doors though.
I would place as normal door objects and use Karl's method to select and change.
Barry.
One of the forum moderators.
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