no, it doesn't change but i closed the client and reseted the pass key at the same time so i couldn't tell which is the problem. the last time it happened i only changed the passkey and ratio stopped to decrease. so i bet on pass key

now i opened the client again, same client. if ratio starts to decrease again the problem is due to client but if it doesn't someone uses my passkey somehow.

thank you for your help and i'll let you know.

Use a different client. I'm partial to RUtorrent, Deluge, and Qbittorrent myself.