How to assign other vst sounds for the playback

can anybody please explain me ,step by step, how to assign other vst libraries sounds (…from Spitfire , VSL…etc) instead of using Halion sounds?
I have Dorico Elements 4.3 version.

You need to first load the plug-ins you want to use into the rack via the VST and MIDI panel in the left zone in Play mode:

Then once you have loaded the plug-ins, use the Track Inspector panel in the same location to change the sound for the selected track in the track overview:

…I guess I’m doing something wrong. After i have loaded into the rack the plug ins, although I assign (in the track inspector) each different instrument, at the end the playback is always with the same instrument (for example the woodwinds tracks will play all the last one assigned…the bassoon …) this with BBC Symph. and/or Synchron.

I guess the issue is that after you switch back to the Track Inspector panel, you’re not selecting the instrument you want to change the sound for in the track overview in Play mode. The track overview is the main display to the right of the left zone, and you need to select the track corresponding to the instrument whose routing you want to change before you make any changes in the Routing section.

Got it!