Blurry Display

I have a wide Acer monitor which was working fine until I tried to set up a (free! old!) 2nd monitor a few days ago. First I got the message that the monitor was out of range, and I changed some settings based on googling the issue. After a reboot, I got the 2nd monitor up but in order to have a readable display on both monitors, I changed some other settings. My main monitor was less crisp, but OKish. Sadly, I did not document the changes I made and can't recall what I did.
Unfortunately, my computer couldn't detect the 2nd monitor and I gave up and disconnected it from my system. Now my Acer is a blurry mess. I've tried adjusting the custom scaling settings to no avail. Various settings change the size from OK to huge, but all versions are very blurry. [The recommended screen resolution makes everything too small. Software without a zoom feature is uncomfortable to read.] There is the ominous message that changing the scaling may make it difficult to go back to the original settings.
HELP!
Thanks
Tech Support Guy System Info Utility version 1.0.0.4
OS Version: Microsoft Windows 10 Home, 64 bit
Processor: Intel(R) Core(TM) i5-4460 CPU @ 3.20GHz, Intel64 Family 6 Model 60 Stepping 3
Processor Count: 4
RAM: 8108 Mb
Graphics Card: Intel(R) HD Graphics 4600, 1024 Mb
Hard Drives: C: 917 GB (693 GB Free); E: 298 GB (16 GB Free);
Motherboard: Dell Inc., 088DT1
Antivirus: Kaspersky Internet Security, Enabled and Updated