With Multi dlls associated with GTT, Any new device added to Room gets associated with current Default Library.
Already existing device will be still working on the dll which it had got associated previously, provided association had done with O version of GTT or dll is loaded before project is imported to GTT.
Device instance association with a particular dll, is displayed by property of the device instance as shown below.

To change device association with dll, we have to click on the button highlighted in the above image.
A New popup window is open on click of the Audio Library Version button as shown below.

In the Audio Library Version Editor a combobox with all the GTT known xAF dlls file version are listed.
Choose desired dll file version and then press Save.
Device will start work with the associated file.
If Device has signal flow with audio objects in it created in some other version, compatible audio objects are upgraded automatically.
In Signal Flow Designer, non compatible audio objects will be highlighted in blue or shown in compiler as warning, these audio objects can be upgraded using audio object context menu.
Press of Cancel will not save any choice of association made.
In following Cases Device association with a dll cannot be changed.
- If signalflow of a device is open
- If monitoring window like a streaming window or profiler window is open
Note: Change of dll association for one device will not impact other device instance