With the Fantasy Grounds Unity update 2021-12-15, the Sidebar underwent a transformative and functional update.
Users used to have to choose which buttons or groups of buttons they needed for their game. This system as been replaced with a new collapsible group system that will be discussed below.
There are no longer settings in Options for the Sidebar.
Another update, v4.1.14 on 2022-03-03, added the vertically-collapsible Sidebar toggle allowing for three different configurations. This feature was added after the Collapsible Sidebar video tutorial at the bottom of the article.