KenK wrote:

Microtek 815c.

Also, that monitor is probably around 16 years old. I saw a user in a
forum note in 2014 that he had this monitor for 11 years, so 5 years
later that monitor is now 16 years old. CRTs go out of focus which
cannot be adjusted out. They also lose brightness, and upping the
brightness results in loss of focus or contrast. Could be you've been
upping the brightness to compensate for a corroded cathode ray gun (the
heater). There is a trick of overheating the filament to burn off the
corrosion but it is hazardous: at the higher temperature and current,
the emitter could burn out and the monitor goes dead (no electrons
anymore to illuminate the phosphor on the inside of the screen). Shops
used to do that trick but had the customer sign a waiver acknowledging
the attempt could result in a completely dead CRT monitor. I did it
once accidentally when I reattached the multi-pin connector on the back
of the tube's neck resulting in the wrong voltage on the heater,
overheating it, realized what I did when the screen became very bright,
removed and repositioned the connector (you'd think they'd be
polarized), and the monitor was bright and I even had to turn down the
brightness. Gee, I fixed it. Luckily that was back in tech school and
any CRTs sent there for repair were waivered because they had students
working on them.

With such an old monitor, and with almost no shops working on them
anymore, try lowering the brightness to reduce the bloom of the
characters. That could result in an overly dim monitor that would have
sharper but dimmer characters, so just as hard to read as before. You
can't get around CRTs getting old and losing brightness and focus. Time
to start budgeting for a new monitor. If it's an LCD/LED, make sure you
set the screen resolution in Windows the same as the monitor's native
resolution. You get fuzziness if you set the Windows resolution
different due to interpolation between pixels.