[GNC] How does GnuCash autoassign transactions?

[Joseph Vernice]

I would like to know how GnuCash auto-assigns transactions that are 
downloaded and imported?  Also, how can these transactions be changed 
for future imports?

Example: I import a set of transactions and some are assigned as an 
Expense:Charity, some are assigned as Income, some as Imbalance.  Most 
of the time only a handful of these are correct. How are the 
transactions PREDICTED?  How can this be tweaked?

Thank you,
Joseph Vernice