Increase value using LCD Keypad Shield

Using Arduino Programming Questions
1

Hi,

I'm trying to create a kind of quiz. Depending on the right answer, my arduino will give a clue for the next question.
I'm using the arduino lcd keypad shield and Arduino Uno.

With the up and right button I want a counter to increase (visibleAnswer++).
Down/left should decrease the counter.

But when I press the button, it increases with a random number.
I've tried to implement the debounce example but then only my Up button works.

Can anyone please help?

Here's my code:

#include <LiquidCrystal.h>

LiquidCrystal lcd(8, 9, 4, 5, 6, 7);

// define some values used by the panel and buttons
int lcd_key     = 0;
int adc_key_in  = 0;
#define btnRIGHT  0
#define btnUP     1
#define btnDOWN   2
#define btnLEFT   3
#define btnSELECT 4
#define btnNONE   5

// read the buttons
int read_LCD_buttons()
{
 adc_key_in = analogRead(0);      
 if (adc_key_in > 1000) return btnNONE; 
 if (adc_key_in < 50)   return btnRIGHT;  
 if (adc_key_in < 195)  return btnUP; 
 if (adc_key_in < 380)  return btnDOWN; 
 if (adc_key_in < 555)  return btnLEFT; 
 if (adc_key_in < 790)  return btnSELECT;   

 return btnNONE;  
}

char* answer[] = { "a", "b",  "c"};
int visibleAnswer = 0;


void setup()
{
 lcd.begin(16, 2);              
 lcd.setCursor(0,0);
 lcd.print("Push the buttons"); 
}
 
void loop()
{
 lcd.setCursor(9,1);           
 lcd.print(visibleAnswer);
 lcd.setCursor(0,1);            
 lcd_key = read_LCD_buttons();  
 switch (lcd_key)               
 {
   case btnRIGHT:
     {
     lcd.print("RIGHT ");
     visibleAnswer++;
     break;
     }
   case btnLEFT:
     {
     lcd.print("LEFT   ");
     visibleAnswer--;
     break;
     }
   case btnUP:
     {
     lcd.print("UP    ");
     visibleAnswer++;
     break;
     }
   case btnDOWN:
     {
     lcd.print("DOWN  ");
     visibleAnswer--;
     break;
     }
   case btnSELECT:
     {
     lcd.print("SELECT");
     CheckAnswer(visibleAnswer);
     break;
     }
     case btnNONE:
     {
     lcd.print("NONE  ");
     break;
     }
 }
}

 void CheckAnswer(int answer){
  //Do something
 }
2

What evidence do you have that the pin needs debouncing? The switches may bounce (most likely they DO bounce). But, the switches are connected to various values of resistors that are then connected to a single analog pin. The ADC will filter out the bouncing, since it is a slow device.