If you want to run ads or optimize ad sets in an ad account that does not own the pixel, you must assign (share) the pixel with that ad account inside Meta Business Settings.
Step-by-Step: Assign a Pixel to an Ad Account
Step 1: Open Business Settings
Go to Meta Business Settings
In the left-hand menu, open Data Sources
Click Pixels
Step 2: View All Pixels
You will see a list of all pixels available in this Business Manager
Click on the pixel you want to assign
Step 3: Open Connected Assets
With the pixel selected, go to the Connected Assets tab
This tab shows all ad accounts currently assigned to the pixel
Step 4: Assign the Ad Account
Click Add Assets (or Assign Ad Accounts)
Select the ad account(s) you want to assign this pixel to
Confirm the assignment
Once assigned, the ad account will appear in the Connected Assets list.
