About bayesian configuration

[fishy]

There're 2 bayesian thresholds:
bayesian_filter_spam_probability_treshold (0.9 now)
bayesian_filter_nonspam_probability_treshold (0.2 now)

I feel that the bayesian filter is too strict now, it treat some non-spam comments as spam, so I want to do some adjust, but these 2 thresholds make me confused (I only have experience on a bayesian filter with only 1 threshold), how do I do to make it not so strict?

for example:
bayesian_filter_spam_probability_treshold + (e.g. 0.95)
bayesian_filter_nonspam_probability_treshold - (e.g. 0.1)
?