How to change the display of letters with gray tones

I installed the OpenSuse 13.2 64-bit and KDE, it is great, it’s a really top job,

However, I have 71 years and my eyes are not as accurate as before.
Most small windows such as the address in the browser, the date and time on the taskbar, are in letters on gray tone.
For my case, it would be better than nothing was shown in gray tones.

It would be wonderful if at the moment of installation, there was an option to configure the system to a more appropriate visual for those who have vision problems.

I wonder if there is a way to change all gray tones to black at once for the entire system.

Thanks in advance.

I changed the desktop theme from “openSUSElight” (the default) to “openSUSE” (was the 13.1 default) to get better contrast.