PaulS:
Based on what? How will the Arduino know that you want to increase OnTime? To decrease OffTime? By how much? Pressing the switches
In the last code i send .i removed my change of using switch and EEPROM .because i made many attempts but i faild .may be my attempts .in the other side i tried small examples for incease and decrease using switches and it was ok .by when i apply this in my code i fail.may be because i'm still beginner .