I can't say how you can increase trust, but from a mathematical point of view you seem to be running some sort of HYIP:
You made 4000 USD in 1.5 years. You turned a 200000% profit.
200 = e ^ (x * 365 * 1.5)
Take the natural log to both sides:
5.298 = x * 365 * 1.5
Divide the left by the right to solve for x :
x = 0.968 percent increase compounded
DAILY!That is way too high.
If you want to have an investment engine that is built on trust...just look at the currency you are using now: bitcoin.
http.://gethashingforum.com/set up an account and make a general post asking your question. The guys there will be of service.