Are there any setting on the monitor to change like ne that concern sharpness or similar?

Try a different connection type. That monitor has both HDMI and VGA. I suspect y are using HDMI and not infrequently that type of connection is is not that good. With HDMI there is an overscan setting in the Mac Display preferences. Try changing that

Also see:

Text looks blurred on Samsung display

Re: Blurry Text On Dell UltraSharp U3014

On the monitors on board controls , is there a control to show type of input?  Possibly Display Input or HDMI Input that has a menu for the different hook-ups.If yes check to see if PC is available.  If so try it, this was a solution in several other instances involving Samsung Displays.

Just out of curiosity, does the menu bar show correctly on the display?

In the Apple Display Preferences is it set to Resolution: Default set for Display or scaled?  Possibly scaled if not used will offer a higher resolution.  This sounds to be the problem by your description of the display.  I would assume you should be able to get 2560 X 1440 or something there abouts. I stand corrected I see the max resolution is 1920 X 1080.

I was looking through the manual and all I can see left to try is Image size in the Screen Set Ups.  I worked with several plain HD TV's with success but it was mainly always with the Overscan on the TV and the Underscan on the Mac.

when I check all the settings its is showg as a TV

The Samsung S27E390 is a TV, not a computer display.

The native resolution of this TV is 1920x1080 and the only input connector is HDMI.

SiR0gers wrote:

 

None of the text is a crisp as it should be and all of the browser pages seem rather large.

 

Those are poor spec's (1920 x 1080) for a 27" monitor. A decent 27" computer monitor for use with an iMac or Mac Mini sould have 2560 x 1440 resolution and either dual-link DVI or DisplayPort inputs. 

Agreeing with den.thed the resolution should be higher.  Have you given SwitchRes X a thought?  Possibly forcing a higher resolution would solve the problem.