Screen does not work as before?

Urgently need your help.

I'm currently in homeschooling, but I had the following problem.

I have a DP connection on my mainboard on my OptiPlex 3020 PC because I have the integrated graphics chip of my I3 4160. Only an HDMI connection on my screen. So I got an adapter so nice, so good but when I opened the PC, the quality / sharpness / resolution was much worse. I also tried a laptop and I ran into the same problem. I have no idea what to do now. The PC is very important to me and I need it for my lessons.
Thanks in advance

Just contact us if you have any questions.

The monitor will likely support a different resolution than your laptop. You have to set the screens to extended mode and then you can specify a different resolution for the laptop and monitor. The standard resolution is best used for the monitor, everything else automatically results in a blurred image.

HDMI is also generally less powerful than DisplayPort

I myself need it for the PC

What is the standard resolution of your monitor? Or alternatively, tell us the exact model of the monitor and someone from here will look it up.

So recommended in the settings is 1360 * 768 but then it is not sharp either

That would be a very unusual monitor setting. Which monitor do you have exactly? So make and model