Welcome. You took a big leap.
In the Places view, the places are sorted in a hierarchy from largest to smallest. In a complete name there would be Country, State/Province all the way down to the number on the house. During the upgrade, Gramps built the hierarchy based upon the previous name records as you entered it.
In Preferences, the fist settings on the Data tab defaults to use Automate Place format:. This option builds the total place name up through the hierarchy. On the Place record, in the Name field, all you see is the name of place at that level in the hierarchy. The full name is generated and displayed at the top for that record.
Unchecking Automate Place format: takes you back to the static Place name you were used to in 3.4.9. The hierarchy remains to organize the list, but now when you edit a place record, you will see a Title field. This is the record as you entered it and what will display when attached to an event.
And notice that you have two ways to view the list of places. One is the Place Tree, the sorted list using the hierarchy. The other is Places. A flat list of each place record. Note each column can be sorted. And which columns to display and in what order can be modified using the views configure settings. 
on the tool bar. You can drag the columns into a different order. The first column will be the default sort for the view. All views have this configure option.