it's not a problem at all. The refresh rate is just how many times the monitor updates the picture on the screen. So now u are getting 75 pictures per second.
I can clearly see 75hz flickering, I can even sometimes see my 85hz flickering.
Try the different ones and see which fits u the best.
Right click on desktop, properties (I think, it should be the lowest one) then settings and then advanced.
Then I have no idea what it's called in the english version of windows, but I'd gues it says monitor
and in there u can change the refresh rate.