This is the expected behaviour and you cannot change it. Once you set a Send Relationship in a data extension, for example, Subscriber Key relates to subscribers on Subscriber Key, it will look up the email address from All Subscribers list at send time.
Depending on where your data is coming from, you can set up an automation that will look for differences between your data and All Subs and update All Subs accordingly. Here is an example of how you can set it up if you're integrated with Sales/Service Cloud:
- SQL Query Activity that checks for changed email addresses in your synchronized data extensions and writes them to a temporary data extension.
- Data Extract Activity that extracts the data from your temporary data extension and writes it to a CSV-file
- File Transfer Activity that moves the CSV-file from activity 2 to the Import-folder of your Enhanced FTP
- Import File Activity imports the data from the CSV-file to the All Subscribers list.
Take a look at Markus' blog for more details: https://markus.codes/2017/07/14/how-to-sync-email-changes-from-service-cloud-to-all-subscribers-list
I just found the following article, Profile Center and Marketing Cloud Connect, that says:
Every Marketing Cloud email to a Salesforce contact, lead, report, or
campaign includes a link to the Profile Center where customers manage
their attributes and subscription preferences. These changes update
Salesforce contact and lead data.
If this works as expected, then you wouldn't have to worry about prioritizing Profile Center updates, as they would be reflected in Sales/Service Cloud anyway.