All steps below will take place in Display Settings.
How to Find Display Settings
To get there, Right click your desktop and select ‘Display Settings’. 
Rearrange your Displays
Click on ‘Identify’ and a number will appear on the screen of the display it's assigned to. For example, if #1 indentified the left monitor as display 1 and the right side monitor as display 2. 
Select and drag the display to where you want. To save changes please click Apply. Test your new layout by moving your mouse pointer across the different displays to make sure it works like you expect.
Change Size of your Monitor
Change item size on a display by first selecting a display, then using the Item size slider.
To save changes please click Apply.
Change Main Display
To make monitor 1 or 2 your main display, select the display you prefer and make sure the box below saying "Make this my main display" is checked.
To save changes please click Apply.
If Monitors are Showing as Duplicates
Under “Multiple Displays,” select Extend these displays from the drop-down menu.
To save changes please click Apply.
Change Orientation of your Display
Change the orientation of a display by selecting a display, then selecting either Landscape (default) or Portrait under ‘Display Orientation.’
To save changes please click Apply.
Reference
For more information, please reference the Microsoft article below:
How to use multiple monitors in Windows - Microsoft Support