Hello, thank you for the advice.

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This is done by right clicking on the channel, Select Midi instrument (Patch) and Hi-Q instruments are first on the list.
I didn't know what you mean by "on the channel" but I right clicked the "Base" in the Mixer view, selected Midi instrument, selected Hi-Q instrument, and then I selected Hi-Q 033 01 Bass Acoustic Upright.
I opened the Piano Roll view and I could hear the bass sound.
Then I clicked the Playable Track button, but no message (because it's already Hi-Q instrument?)
and I could hear the bass sound this time!

So I created the mute region and edited some bass notes.
But when I played it, the bass notes disappeared.............