Admin → Settings → Spam
BUT if this is happening I think you probably have an underlying problem that should be addressed, not by tweaking the threshold values, but by evaluating just what kind of community you want to have and why this is happening. .
To highlight my opinion, the settings and their default values are
num flaggers to close topic - default 5
Minimum number of unique flaggers that is required to automatically pause a topic for intervention
num flags to close topic - default 12
Minimum number of active flags that is required to automatically pause a topic for intervention
IMHO these default values are not insignificant.
This means if a topic was closed at least 5 different members saw a problem with it that they felt was bad enough to make them Flag
And that at least 12 Flags were given.
Not every community is “all work and no play” or “all fun and games”
That is, why are members Flagging?
Does the community have different ideas as to what is OK and the more “conservative” are Flagging the more “liberal”? (i.e. are the forum policies spelled out clearly)
Are some members “ganging up” on other members? (do moderators need to become more involved)