Windows 10: how to make my second monitor full screen

I recently had a extra monitor set up one is perfect full screen no matter what I open but the second is not full screen ive tired everything and can get it to go to full screen it has black space on the left and right side about 3"

:)

 

Second monitor screen resolution problem

Hi,

For us to properly isolate the issue with your second monitor screen resolution, we would like to know the following:

• 
  Were there any changes made on your computer prior to the issue (e.g., updates, software installation)?
  
• 
  When did the issue first begin?
  
• 
  To make sure that we have not missed on anything, what troubleshooting steps have you done so far?
  

In the meantime, we suggest that you try resetting your monitor settings, and check if the issue still persists. You may refer to your monitor on how to reset it.

We look forward to your response.

 

Second monitor not detected after update

Hi Tom,

There are several reasons that could have caused the issue you are experiencing. One of these is the update you previously performed in Windows, either it was not configured properly by the system or the update components were corrupted. Kindly answer the
following questions for clarification:

• Have you tried updating the monitor and display drivers?
• Have you tried to use another user profile to check if the issue re-occurs?

Furthermore, we suggest that you add the other monitor manually. This is to ensure that the second monitor is still connected after the update. Here are the steps:

• Type connected devices and open Connected Devices on the
  Windows Search bar.
• Click Add devices.
• Select the Second screen.
• Pick one of the 3 options: Duplicate, Extend, and the Second screen only.
• The Duplicate option will duplicate the primary display to secondary display.
• The Extend option will unite two monitors so you can use them both as one.
• The Second screen only option will, obviously, disable primary and use only the secondary monitor.
• Once you’ve chosen the preferred mode, save changes.

We're looking forward to your response.

 

Returning Windows to Second Screen

Hello Kate,

Let's try to isolate the issue and see what is preventing you from using Windows to second screen. Kindly provide us the following information:

• When you turned on your computer, does it give you an extended display for both monitor screen and your laptop?
• Is your monitor screen already connected to your laptop before turning it on?
• What cable are you using to connect your second monitor to your laptop?
  
• What troubleshooting steps have you tried?