By chance, I figured out how to update the System Last Modified date on a Contact when an Opportunity with that contact is updated. I used the object Deal, with Opportunity - LastModifiedDate- Is changed. My Action was to update the field called Note.
I do not see the text string in the Note of the contact updated, but it does update the contact's system last active.
QUESTION: What object and actions do I use to update the Account name's system last active date when the Opportunity is updated.
End goal: internal corporate create Deals based upon a contact for all activity. We wish to update the Contact last active and the Account last active any time the deal is modified. Final goal- create report on Accounts to show last system activity dates.