Have the Approver show as the modified person in Flow/PowerAutomate

Question

Currently I have a flow running but the Modified column only show my name because I am the flow creator. I want it to update with the approver's name instead.

I tried to use HTTP Request to SharePoint but my screen does not look the same as the solution shown here: Update SharePoint Online item build-in fields via Microsoft Flow. Can the experts give me some guidelines on how to accomplish this?

This is what my HTTP request screen look like:

Answer 1

Just to recap the conversation from the above comments:

In order to use the extend metadata object in a REST JSON POST update to existing Item, the following headers need to be set (this applies whether calling from a Power Automate Flow or some other REST-connected solution):

content-type: application/json;odata=verbose
if-match: *
x-http-method: MERGE

In addition, the type specified within the metadata object should be the name of the ContentType of the item you are attempting to update.