hi pornluver,
Sorry for the late answer.
Regarding the STR lending: our bot is not designed very well for very high rates and high volatility. The STR lending rates have seen large movements, and our bot only check every 1 to 2 minutes (which is quite quick, but not real time). So you may see offers with lower rates than could be at best.
Our main strategy is to maximize the Use rate of your funds, so that it is lent most of the time and bring you back highest rate possible on the long run. As you will see, Lending is most of the time a marathon rather than a speed race.
To watch the details and charts on your STR lending, simply click on the small icon between "Tod. rate" and "Use" in the Overview panel. The charts will change to this currency.
The setting Duration is the maximum amount of time our bot let an offer open, before closing it. It is not the duration of the loan itself. Please click on the title of the settings to see a tooltip box explaining each settings. You can also read the Help page to know more about each strategy.
I hope I answered all your questions. Feel free to join us on our slack channel, if you have more questions. See the link in the footer of the web page.
By the way, thanks a lot to ranlo for his answers.