Thank you for your purchase. You can setup both the things that you are asking for. I have explained below.
1- i need to setup my Sell Sign when the current price hits the highest price of 3 days ago.
You can define a condition for sell signal. You can see attached 'sell-condition.png' and 'sell-signal.png'.
2- i need to set a stop loss. Not at a price. but at a time. Like 7 days from the Entry.
You can setup the force close based on number of candles. You can do that in backtesting dialog. See the attached backtest-with-force-stop.png.
Please let me know if it answers your query.