Enable ClearType on Windows 10

I noticed jagged text on a computer running Windows 10.

It was particularly noticeable with Firefox and Chrome.

 

I opened Advanced display settings and tried to open ClearType text.

 

However this failed with this error message:

C:\Windows\system32\cttune.exe

Windows cannot access the specified device, path, or file. You may not have the appropriate permissions to access the item.

 

Instead I tried to start cttune.exe directly:

 

This was possible and I noticed that ClearType was disabled (as expected).

 

I selected: Turn on ClearType

 

And completed the guide to adjust ClearType optimally.

 

That solved the problem. After enabling and adjusting ClearType, text in all programs looked much better without jagged edges.