Arduino Timer with increase time button
I don't fully understand your program, but I hope to give some guidelines/tips:


Instead of using all kind of different variables, with hour, minutes and seconds, with with only one variable that keeps the time. E.g. a long integer value that contains 24 * 60 * hours + 60 * minutes + seconds as one value. E.g. 12:34:56 will be 24 * 60 * 12 + 60 * 34 + 56 = 19,376.
Subtracting one or 10 seconds will be as easy as subtracting a value 1 or 10.
To calculate back to seconds, minutes and hours, use 3 formulas (assuming time is the time value):



int hours   = (int) time / 60 / 24;
int minutes = (int) (time - hours * 60 * 24) / 60;
int seconds = time % 60;




Keep the code to display the LCD separate, probably it's easier to update every digit every second. You probably change it every second, or when the button has been pressed, which is very slow for a MCU.
When using a button (you already put it in a variable), just remove 10 seconds, and update the time.
However, check also the Blink Without Delay example on the Arduino website, since when you press a button, high likely the button will bounce and one press may result in several times 10 seconds will be subtracted.
And as said above, use good and English variable names, and English comments (except the GUI text to be displayed... O zi buna).