Hi there!
To control which sidebar shows on your events pages, you will need to select a template that has the code to output the sidebar. In Events > Settings > Events Template, you can choose between the default events template, the default theme page template, and any custom page templates you have created.
So, you will need to:
1) Create the custom template
2) Enable it in this setting
To create the template, I would start by making a copy of your theme’s default page template, and then modify it to use the sidebar of your choice. You can find more information about creating custom WordPress templates here: https://developer.wordpress.org/themes/template-files-section/page-template-files/
To learn more about adding a sidebar to your template, check out the documentation for adding sidebars: https://developer.wordpress.org/reference/functions/get_sidebar/
Hope that helps! Please let me know if you have any other questions.
Thanks,
Sky