Hello everyone ... who can explain to me how the problem of the difficulty works

and how can I set a good compromise for my hardware

??
On ckpool I started with difficulty 4000 (4K) but the pool automatically set me to 40 and then to 20 ....
so what should I do??
thanks,ultimate64
You probably selected a port with a vardiff (variable difficulty). If the pool offers a fix diff port you need to select that port & set your diff to reflect an optimal diff. This would require some experimentation.
All that being said, unless you have a specific reason to set fix diff, most pools operate with a very good variable diff & will yield the best results.