This happened to me today and it is beyond aggravating. All of the formatting buttons I need when composing an email are spread across the top of the screen rather than conveniently located within the compose/reply screen.
Even if this was rolled out to "improve aesthetics" as seems to be indicated here: https://answers.microsoft.com/en-us/outlook\_com/forum/all/how-do-i-move-the-message-ribbon-back-to-below/b29f8270-78c6-4d8f-a0d7-e27c3cd315f5, users deserve to have the option to keep the ribbon settings as they were. Especially for those of us that spend ALL DAY ON EMAIL and deserve to opt-out of absurd or inconvenient changes.
Not to mention, Microsoft did not announce this fairly significant change in primary functionality causing people like myself to have to learn on the fly what's going on while working by COMPOSING AND REPLYING TO EMAILS.
Very disappointed in Microsoft. URGH. Please restore the old ribbon settings ASAP.