You can set up and edit the tracking string applied to your Brand Tag (email_XtraLinkParameters) for your Marketing Cloud business unit’s emails. Navigate to Setup >> Data Management >> Parameter Management. Here you can change the information added to click outs via the Web Analytics Connector.

To add the subscriberKey as a parameter add the following to the string below. You can choose another name for the parameter, but choose mcparam to store this variable.
&mcparam=%%subscriberkey%%

Next steps setting op tracking
Now that we have setup the parameter management all click outs via the Email Studio will be supplied with the new variable. These parameters can be then used via Tag Managers or by your web team.