Question of under review -situation I  would be happy to have a short comment by somebody on following simple situation: I submitted my paper in beginning of January. In the end or January the status changed from the administration (Editor) to "under review". After that, this has not changed, it is still "under review". Is this normal. My field is history. 

The journal doesn't indicate the review-times in the pages, but from the same publishing house's pages I have seen other journals of the same field and noted that the time may vary from 3-4 months up to one year.

I have decided that I will patiently wait, but I am starting to feel insecure about if they have forgotten to push the status-button. So, it would be nice just to know, does this sounds normal? Another article a couple of years ago in another journal didn't take that long.
The time frame you mention is within what can be encountered. The time frames also differ wide between disciplines but also from journal to journal so one way to check how reasonable it is will be to check the journal for how long it has taken other papers to go through to acceptance. Many journals state this for each article and hopefully your journal does so as well. If no such information is stated you can try and ask a senior colleague who may have a perspective on the journals and their turn-over times.