I have 2 account one in different currency,
when I enter a transfer between the 2 accounts say from euro to pound I can type the amount in euro and then give the corresponding amount in pound. when I type the amount in pound the computer computes the exchange rate.
However it also discards what I entred in pound. What I entred in pound is replaced by the value in euro*computed rate. 

But the exchange rate is not precise enough it is truncated to 5 digit exemple : 1pound=1.4979euro
if you transfer anything above a 1000 pound or euro you precision is 10 cens and it is not enough
it get worse if you have yens  as 1000 yen are about 1 pound or 100 yuan 1 pound
there are plenty of example like that where Kmymoney gets completly unusable.

2 solutions : increase the resolution of the exchange rate or discard it when the values of the transfer are both entred by the user.

regards