I want ask an easy way to use Sequential and Front and Back First, maybe an setting, to avoid the annoying and slow way of context menu. Thanks

I think this was recently explained somewhere in Tixati's channel forums somewhere...

The reason torrent is getting pieces at random - to ensure the best possible (even) distribution of rarest pieces, that is to keep the torrent alive. It's really at the core of how torrents function, ideally the first guy seeding only needs to upload each piece once to get the torrent going and online forever.
Imagine, 100 people each downloaded 10 sequential pieces - the uploader would see a ratio of 100%, but everyone is stuck at the first couple pieces due to sequential mode.

So this is why is hard. To keep people away from it :)

You can still do "CTRL+A" in the  tab to select everything and then set sequential if you really need it for video streaming or alike. Why do you want it to be enabled all the time?

Granted, I don't see a "Play" button feature (µtorrent) that would enable streaming (sequential) mode and launch a media player as soon as enough pieces were buffered.

I think use it ever is an problem, but I use to movies and series, not ever, but frequently, only when I want watch imediately, no need be automatic, maybe add an button on file selection windows, just to make it a bit more easy.

The whole idea is for it NOT to be easy so that people don't do it. Look at other torrent clients, like Transmission, who out right don't include the feature at all. The current implementation is core to how torrents behave.