This site does not support weight gain as a goal, despite numerous complaints from body builders and pregnant ladies. So you probably need to either ignore it or find another site that does Plenty of forum support for that here though.
If I keep starting over, eventually it will stick, right?
Current weight: 140
Goal weight: 135
I'm trying to gain weight too. I'm also a programmer and I shouldn't think the change to the software would be that great. It might be as easy as turning off the warning that says you need to put a future weight lower than the current weight.
However, I suppose the graphs may be designed for just decreasing displays and if you try to draw and increasing line over time you may need to change the starting coordinates in the display. And this could be a low-priority feature for the development team as well, as they probably have more urgent fires to put out.