Configure Design Tab
When you have a design open, the Design tab displays two tabs: Attributes and Extended Data (or Metadata), as well as any custom tabs you may have developed. You may indicate which tab is selected by default by using a registry key.
Open the Registry and browse to: HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Miner and Miner\ArcFM8\Attribute Editor. Double-click DefaultTabPriority. The Value Data field accepts string values.
If the Attribute Editor key doesn't exist, you may need to create it, as well as the DefaultTabPriority string value.
For example, "Extended Data","Configuration." The Extended Data tab will be selected by default. If it doesn't exist, then the Configuration (custom) tab will be the default. If the Value Data field is empty or the tabs don't exist, the Attributes tab is selected.
The Extended Data tab is available only if you have configured EDM in ArcCatalog. If you modify the Registry while ArcMap is open, you will need to close and re-open ArcMap in order for the changes to become active.