When my workflows run, the SharePoint List modified by shows as "me" rather than the person who triggered the workflow or as "Nintex".
I want the workflow actions in the History of the SharePoint List to show any actions, e.g. Update List, to show as Modified By "Nintex Workflow".
I created a service account, logged in under that account and created a new workflow, but when I run the workflow, it is showing as my name again.
How can I ensure that the Workflow Actions show as run by Nintex Workflow ?
you can add an Action Set action to your workflow and open it's configuration to tick Elevate Permissions.
Now all actions inside the Action Set will be performed with the elevated SharePoint App account instead of the user that kicked off the workflow.
Another option would be to use the office 365 update actions. These allow you to enter a credential from the connection manager. The action will then be performed in the context of the given user.