Mining LTC on Coinotron has a higher rejection (stale) rate than other pools. It is 5+%. It is because the miner-difficulty is too high.

So far the pool finds a block every 11.8 minutes. My miner generate a share every 1.7 min. When the pool finds a block and "close the door for the round", I have have a probability of 1.7min /2  / 11.8min = 5.5% not being able to register the work I have done with the pool. I measured the actual stale rate in 12 hours and it is 5.2%, in good agreement iwth my estimate.

So how can I set the difficulty for me lower? It is 198 now (my miner is 160kH/s). I would like to get the difficulty 60 or lower.