MCSA BI Reporting Certification Prep

Hi!  It is my intention to earn the MCSA BI Reporting certification.  I've already passed the 70-779 (PBI Excel) exam.  Working on preparing for the 70-778 exam.  The exam covers three areas: comsuming and transforming data in PBI Desktop, Modeling and Visualizing Data and Dashboards, Reports and Apps in the PBI Service.  Resources I've used:

• The MS Press 70-778 exam prep book
• Three courses from Udemy: Power BI Master Class - Consume and Transform Data, Power BI Master Class - Data Modeling and DAX Formulas, and Power BI Master Class - Dashboards and Power BI Service
• Another course from edX (still in progress): Analyzing and Visualizing Data with Power BI

I tried including links to each of these resources, but apparently linking to them is invalid, but if you Google you'll probably find them.

I use Power BI extensively at work, and I feel very comfortable with the first two topics.  But I've never had responsibility for administering the PBI service so I feel very uncomfortable with the third section.  The online courses don't seem to cover these topics in great detail either.  Plus throw in how rapidly Microsoft is developing Power BI, I wonder if these materials might be somewhat dated.

Can anyone recommend any resources to prepare, especially for the third section of the exam?  Any advice - especially from those who have earned the certification - would be most appreciated!  Thank you!