[mrtg] Problems setting/saving threshold

[jack at loserville.org]

Sorry in advance if this is a bonehead question. Either I haven't found the answer or I looked right at it and didn't understand it. 

We have an installation that monitors 100 servers or so. There is one machine that consistently gets twice as much traffic on the ethernet interfaces as the threshold that is set in the .cfg file for that machine. 

There are two issues. I've changed the threshold for those interfaces in the file machinename.cfg, but that doesn't seem to have any effect. The threshold used by MRTG doesn't change. Am I setting it in the wrong place? Second, the changes that I make to that file are eventually overwritten when cfgmaker runs. What am I missing? How do I make this change and prevent it from being overwritten by cfgmaker? 

Thanks.