How to set a custom Ruby version with cPanel and EasyApache 4

I’m on a shared server with cPanel, EasyApache4 and Phusion Passenger.
My app was running fine with ruby 2.1.6 (in a shared directory) and rails 4.2.6.
I had a .htaccess file:

PassengerEnabled on 
PassengerLoadShellEnvVars On 
PassengerAppRoot /home/adminxxx/webapps/assist2prod/current/ 
PassengerRuby /usr/local/ruby20/bin/ruby

## General Apache options 
#AddHandler cgi-script .cgi 
#Options +FollowSymLinks +ExecCGI

# Redirect all requests not available on the filesystem to Rails 
RewriteEngine On 
RailsEnv production 
RackEnv production

#ErrorDocument 500 "<h2>Production Application error</h2>Rails application failed to start properly"

The server decided to upgrade and now I have to use the cPanel Application Manager to set up my app. I discovered the new .conf file:

<Location "/">
    <IfModule mod_env.c>
        SetEnv "PassengerRuby" "/usr/local/bin/ruby"
        SetEnv "RackEnv" "production"
        SetEnv "RailsEnv" "production"
    </IfModule>
    
    <IfModule mod_passenger.c>
        PassengerAppEnv "production"

        PassengerEnabled on
        PassengerBaseURI "/"
        PassengerAppRoot "/home/adminxxx/webapps/assist2prod/releases-2021old/20190707101851"
        PassengerAppGroupName "adminxxx - WisdomTorontoProduction"
        PassengerNodejs /opt/cpanel/ea-nodejs10/bin/node
    </IfModule>
</Location>
<Directory "/home/adminxxx/webapps/assist2prod/releases-2021old/20190707101851">
    Allow from all
    Options -MultiViews
    Options -Indexes
    Require all granted
</Directory>

Here’s some info:

# /usr/local/bin/ruby -v
ruby 2.1.6p336 (2015-04-13 revision 50298) [x86_64-linux]

# /usr/local/ruby20/bin/ruby -v
ruby 2.0.0p648 (2015-12-16 revision 53162) [x86_64-linux]

Now, when I enable the app in Application Manager I get this in the apache log file:

App 792497 output: Error: The application encountered the following error: Your Ruby version is 2.4.10, but your Gemfile specified 2.1.6 (Bundler::RubyVersionMismatch)
App 792497 output:     /opt/cpanel/ea-ruby24/root/usr/local/share/gems/gems/bundler-2.2.27/lib/bundler/definition.rb:441:in `validate_ruby!'
App 792497 output:     /opt/cpanel/ea-ruby24/root/usr/local/share/gems/gems/bundler-2.2.27/lib/bundler/definition.rb:416:in `validate_runtime!'
App 792497 output:     /opt/cpanel/ea-ruby24/root/usr/local/share/gems/gems/bundler-2.2.27/lib/bundler.rb:143:in `setup'
App 792497 output:     /opt/cpanel/ea-ruby24/root/usr/local/share/gems/gems/bundler-2.2.27/lib/bundler/setup.rb:20:in `block in <top (required)>'
App 792497 output:     /opt/cpanel/ea-ruby24/root/usr/local/share/gems/gems/bundler-2.2.27/lib/bundler/ui/shell.rb:136:in `with_level'
App 792497 output:     /opt/cpanel/ea-ruby24/root/usr/local/share/gems/gems/bundler-2.2.27/lib/bundler/ui/shell.rb:88:in `silence'
App 792497 output:     /opt/cpanel/ea-ruby24/root/usr/local/share/gems/gems/bundler-2.2.27/lib/bundler/setup.rb:20:in `<top (required)>'
App 792497 output:     /opt/cpanel/ea-ruby24/root/usr/share/rubygems/rubygems/core_ext/kernel_require.rb:55:in `require'
App 792497 output:     /opt/cpanel/ea-ruby24/root/usr/share/rubygems/rubygems/core_ext/kernel_require.rb:55:in `require'
App 792497 output:     /opt/cpanel/ea-ruby24/root/usr/share/passenger/phusion_passenger/loader_shared_helpers.rb:365:in `activate_gem'
App 792497 output:     /opt/cpanel/ea-ruby24/root/usr/share/passenger/phusion_passenger/loader_shared_helpers.rb:221:in `block in run_load_path_setup_code'
App 792497 output:     /opt/cpanel/ea-ruby24/root/usr/share/passenger/phusion_passenger/loader_shared_helpers.rb:529:in `running_bundler'
App 792497 output:     /opt/cpanel/ea-ruby24/root/usr/share/passenger/phusion_passenger/loader_shared_helpers.rb:220:in `run_load_path_setup_code'
App 792497 output:     /opt/cpanel/ea-ruby24/root/usr/share/passenger/helper-scripts/rack-preloader.rb:91:in `preload_app'
App 792497 output:     /opt/cpanel/ea-ruby24/root/usr/share/passenger/helper-scripts/rack-preloader.rb:189:in `block in <module:App>'
App 792497 output:     /opt/cpanel/ea-ruby24/root/usr/share/passenger/phusion_passenger/loader_shared_helpers.rb:382:in `run_block_and_record_step_progress'
App 792497 output:     /opt/cpanel/ea-ruby24/root/usr/share/passenger/helper-scripts/rack-preloader.rb:188:in `<module:App>'
App 792497 output:     /opt/cpanel/ea-ruby24/root/usr/share/passenger/helper-scripts/rack-preloader.rb:30:in `<module:PhusionPassenger>'
App 792497 output:     /opt/cpanel/ea-ruby24/root/usr/share/passenger/helper-scripts/rack-preloader.rb:29:in `<main>'
[ E 2021-10-15 17:49:04.3920 983139/T8j age/Cor/App/Implementation.cpp:221 ]: Could not spawn process for application /home/adminxxx/webapps/assist2prod/releases-2021old/20190707101851: The application encountered the following error: Your Ruby version is 2.4.10, but your Gemfile specified 2.1.6 (Bundler::RubyVersionMismatch)
  Error ID: cf24ad74
  Error details saved to: /var/run/ea-ruby24-passenger/passenger-error-cRgyLU.html

So, I’m wondering what is going on:
Does this package force itself to be used by passenger, i.e., overriding PassengerRuby?
Have I misconfigured or missed some setting or env variable?
Am I asking the right questions?
All help appreciated!!!
It’s been a month now, and server admins keep telling me I’ve not configured the paths correctly, etc., but my stomach tells me to write you instead! (Thanks JP!)