Arduino simultaneous push button for a counter
while (digitalRead(pbutton1) == HIGH); This blocks execution so nothing else can happen while the button is pressed. To avoid continous updating of the var while the button is pressed, create 3 booleans that keep track of the button state.

bool button1_is_pressed = false;
....
// If the button is pressed AND it was not previously pressed
if (digitalRead(pbutton1) == HIGH &amp;&amp; !button1_is_pressed) {
    button1_is_pressed = true;
    lcd.print(count++);
}
// Not pressed - reset state variable
else if (digitalRead(pbutton1) == LOW) {
    button1_is_pressed = false;
}


Do this for the other buttons as well.