Hello,
I know I can see the signal graph of every wireless client in the “Quick set” tab (Winbox). Can this graph be seen in any other window besides “Quick set”?
I don’t know why, but my old settings show up in the “Quick set” tab and I don’t want to push the OK button accidentally and revert my current configuration to the old one 
Thanks for your help.
You can see them in Wireless → Registration
Well, there I can see only the graph below (no signal history as in graph in the “quick set” tab). Any other ideas mybe?
The history you see in quick set is stored only while you keep it open I think, so it is not a very good tool. It is made to help you setup the device, align the antennas and that’s it.
You can get those wireless signals by snmp and graph them with Cacti or similar snmp collecting software.