To configure the bottom bar actions, tap 3-dot Menu in Mail View | More Options | Configure Menu.
You should set 4 Actions.Already Selected Actions will be Greyed Out.
Already Selected Actions will be Greyed Out.
| 
| Snooze+ | | 
| Snooze Default | | 
| Done/Undone | | 
| Mark Read | | 
| Mark Unread | | 
| Archive | | 
| Delete | | 
| Reply All | | 
| Reply | | 
| Forward | | 
| Move | | 
| Star/Unstar | | 
| Block | | 
| Quick Replies |
Another way to access the settings is by going to: More... | Global | Customize Menus | Configure Action Buttons | Configure Email Bottom Bar Actions