I've been playing it by ear over the past two years, but; I now want to see how to really do it ... set audio amplitudes for various vocal tracks to roughly the same amplitude or playback volume.  Doing it is not  terribly forthcoming. I am not familiar enough with the vertical meters above the FX box but I suspect they have something to do with resolving my issue!

Have you tried VU meters?
https://klanghelm.com/con...products/VUMT/VUMT.php

I suspect that is what the vertical meters are all about!  Right?
 

I just listen and use the meters to help me avoid clipping.

I always say listen with your ears and not your eyes.

While even a robot could match signal levels to a meter setting, that is usually not what you want. Even "loudness" meters miss some very important aspects of what makes sounds seem loud. A singer with a raspy whiskey voice may well need more raw amplitude than one with a crystalline pure tone or one whose style is ornamented shouting. Even in an ensemble, it is common to treat each vocal track individually to bring out the voice(s) that are making the point. The meters will reliably predict clipping, but will not substitute for judgement.

It would be helpful to say more about what you're doing, or how you got to the question.
If these are tracks you record in a process of over dubs, hopefully you'd want to have establish and keep some nominal record level, and that would result in at least fairly consistant levels.
From there, by ear, jumping from ones similar and good where they ought to be, to ones that need to be tweaked up or down -to fall into this 'norm.
On separate tracks? Set via track -or clip 'gains. In and on a composite track? ..clip gains (a single automation line saves the change), and/or track automation lines. (I'd do it on the clip gains as it leaves track automation open for the final mix tweaks :>)
 
 

Get a good meter in your plug in arsenal. Preferably a K system meter.
One must follow the signal from I/O to obtain similar results across the board.
The gain knob which feeds the plug ins input all the way to the volumes output to the master bus/hardware bus.
 
Its not always practical to have all tracks at the same level because EQ and other plug ins like Reverb, delays, chorus, exc add gain to tracks. you must eliminate/isolate those tracks before metering.