After some time, the best strategy is to have very low level of the first 4 quests, exploration mode, and have high levels boss and other quests, because you will earn almost nothing on the first 4 quests
And there i another glitch:
When you click the second button to move to a new farm, all the money got between that and the beggining of a new game will be used on that new game, so, i advise to farm the wheat only after that...
fixed, I think.