Enabling auditing on an Incident field

[Lockstep]

Hi all, 

I am trying to enable auditing on my 'environment' field for Incidents. Enabling auditing should help us to create reports about which users are updating that field, which will in turn give us the data we need to see which users are participating in triaging incidents as they come in. 

I am logged in using the admin privileges, and have even elevated my privileges to 'security admin', but I cannot enable the audit field as you can see in my attached screenshots. Is there another way of achieving what I want to do here, or have I missed a step? 
I asked ChatGPT and it said updating glide.sys.audit_fields would allow me to do this, but I don't have a gliderecord for that. 

Any help would be amazing, I will be marking as helpful so PLEASE help. Thank you. 

[Mark Manders]

What a terrible name for the field:  'u_choice_2'. This field has been created without paying attention to what was being done. But if the audit on the table is set to 'true' your field automatically should be audited as well. 

Or check here: https://support.servicenow.com/kb?id=kb_article_view&sysparm_article=KB0685670

https://support.servicenow.com/kb?id=kb_article_view&sysparm_article=KB0723730