When you switch a connection, the Developer tool retains the table owner name of the data object. You can manually edit the table owner name in the data object properties, if required.
If you set the table owner name to blank and switch the connection, you can successfully preview the data only if the table exists in the default schema or public schema of the database that the new connection points to. Otherwise, the data preview fails. You must manually update the table owner name in the run-time properties of the data object to successfully preview the data.