Steps to Create
1. Create a Last Field Change Time custom field
Log into your Jira instance as an Administrator.
In the upper right corner of the window, click Settings ( ⚙️ ) and select Apps.
In the left-hand sidebar, click Jira Misc Custom Fields.
Click My custom fields and in the upper right corner click New custom field.
Enter a name for your custom field and, optionally, a description.
Select Last Field Change Time and click Next.
Select the screens to which the new custom field should be added. Click Next.
Configure the field (Figure 1, right) by setting Field to watch to
Flagged
.Click Save.
2. Configure Custom Field Context (Optional)
When a custom field is created, it is added to the selected screens, but it is also added to every issue type and every project. If a custom field should only be added to specific issue types and/or projects, you need to edit the custom field context.
Open the custom field configuration:
From the My Custom Fields page, click the Contexts link for the new custom field.
Through the native Jira menus:
In the upper right corner of the Jira window, click Settings ( ⚙️ ) and select Issues.
In the left-hand panel, click Custom fields.
Locate your new custom field in the list and click Action at the far right. Select Contexts and default value.
Update the context for your custom field as necessary:
To add a new context, click Add new context.
To update the existing context, click Edit context or Edit Configuration.
For specific steps on modifying contexts, see this page: https://support.atlassian.com/jira-cloud-administration/docs/edit-a-custom-field-context/