navigation bar moved to left

I was able to get it to go back by turning off the switch next to "Try it Now" after Coming Soon (upper RH corner in the toolbar), and then restarting Outlook.

However, my understanding is that this change is going to be forced in the future. I am VERY frustrated because this new format takes up significant screen real estate on the left side - 1/2" of my 14" diagonal laptop screen - taking that space directly away from the Preview Pane, which is where I spend about 85% of my Outlook time.