Changes in theme from March 2018

I am the web developer for the link that is attached. The client alerted me last week that they noticed the site suddenly looked different – the masthead and navigation changed appearances and the home page slideshow disappeared. I logged into the dashboard and went into “theme/customize” and saw the specs for the home page slideshow intact. However, I noticed that the Coller theme was updated March 23rd, and wonder if this “major upgrade” changed these aspects of the site? (the same thing happened in January when a Coller upgrade occurred).
What is the best way to respond to this upgrade in regards to retaining the original look of the site?

The page I need help with: [log in to see the link]