Issues with TFT LCD Touchscreen and Arduino mega

Other Hardware Displays
3 
//load required libraries
#include "Adafruit_GFX.h"
#include "Adafruit_TFTLCD.h"
#include "TouchScreen.h"
#include <OneWire.h> 
#include <DallasTemperature.h>

//set touchscreen input pins
#define YP A3
#define XW A2
#define YW 9
#define XP 8

#define TS_MINX 100
#define TS_MINY 120
#define TS_MAXX 920
#define TS_MAXY 940

TouchScreen ts = TouchScreen(XP, YP, XW, YW, 300);

#define LCD_CS A3
#define LCD_CD A2
#define LCD_WR A1
#define LCD_RD A0
#define LCD_RESET A4

Adafruit_TFTLCD tft(LCD_CS, LCD_CD, LCD_WR, LCD_RD, LCD_RESET);

#define MINPRESSURE 10
#define MAXPRESSURE 1000

//Set up TFT colours
#define BLACK 0x0000
#define BLUE tft.colour565(50, 50, 255);
#define DARKBLUE 0x0010
#define VIOLET 0x8888
#define RED 0xF800
#define GREEN 0x07E0
#define CYAN 0x07FF
#define MAGENTA 0xF81F
#define YELLOW 0xFFE0
#define WHITE 0xFFFF
#define GREY tft.colour565(64, 64, 64);
#define GOLD 0xFEA0
#define BROWN 0xA145
#define SILVER 0xC618
#define LIME 0x07E0
#define PINK tft.colour565(255, 0, 255);

//Set temperature probe input
#define ONE_WIRE_BUS 22 
OneWire oneWire(ONE_WIRE_BUS); 
DallasTemperature sensors(&oneWire);

//Set varibles to run menu codes
int currentpage = 0; //0=homescreen, 1=waterchange menu, 2=temperature sensors.....

void setup()
{
// initialising touch screen display
tft.reset();
tft.begin(tft.readID());
Serial.begin(9600);
Serial.println();
Serial.print("reading id....0x");
delay(500);
Serial.println(tft.readID(), HEX);

tft.fillScreen(BLACK); //fill screen with colour
tft.setRotation(1); //horizontal orientation
tft.setTextSize(3); //set size of font
tft.setTextColor(WHITE); //set colour of text

Serial.println("Dallas Temperature IC Control Library Demo");
 sensors.begin();
}
//Draw menu screen
void drawHome()
{
  tft.fillScreen(BLACK);
  tft.fillRoundRect(60, 180, 200, 40, 8, RED); // sensor menu
  tft.fillRoundRect(60, 130, 200, 40, 8, RED); //waterchange menu
  tft.setCursor(60, 20);
  tft.setTextSize(2);
  tft.setFont();
  tft.setTextColor(BLACK);
  tft.setCursor(65, 195);
  tft.print("   Monitoring");
  tft.setCursor(105, 145);
  tft.print("   Waterchange");
  delay(500);
}
// Draw Waterchange Menu
void drawWC()
 tft.fillScreen(BLACK);
  tft.fillRoundRect(60, 100, 100, 40, 8, BLUE); // WC 10%
  tft.setCursor(20, 20);
  tft.setTextSize(2);
  tft.setFont();
  tft.setTextColor(WHITE);
  tft.setCursor(65, 115);
  tft.print("  WC 10%");
  tft.fillRoundRect(60, 150, 100, 40, 8, BLUE); // WC 20%
  tft.setCursor(20, 20);
  tft.setTextSize(2);
  tft.setFont();
  tft.setTextColor(WHITE);
  tft.setCursor(65, 165);
  tft.print("  WC 20%");
   tft.fillRoundRect(60, 200, 100, 40, 8, BLUE); // WC 50%
  tft.setCursor(20, 20);
  tft.setTextSize(2);
  tft.setFont();
  tft.setTextColor(WHITE);
  tft.setCursor(65, 215);
  tft.print("  WC 50%");
  tft.fillRoundRect(180, 100, 100, 40, 8, DARKBLUE); // Top up
  tft.setCursor(20, 20);
  tft.setTextSize(2);
  tft.setFont();
  tft.setTextColor(WHITE);
  tft.setCursor(185, 115);
  tft.print("  Top-up");
  tft.fillRoundRect(180, 150, 100, 40, 8, DARKBLUE); // Drain
  tft.setTextSize(2);
  tft.setFont();
  tft.setTextColor(WHITE);
  tft.setCursor(185, 165);
  tft.print("  Drain");
  tft.fillRoundRect(870, 900, 50, 30, 8, RED); //Return Button
  tft.setCursor(885, 915);
  tft.setTextColor(BLACK);
  tft.print("<-");
  delay(300);
{
//Draw water monitoring menu
void drawMonitor(); 
tft.fillScreen(BLACK);
  tft.fillRoundRect(60, 60, 50, 200, 8, BLUE); // Q1
  tft.setCursor(20, 20);
  tft.setTextSize(2);
  tft.setFont();
  tft.setTextColor(WHITE);
  tft.setCursor(65, 115);
  tft.print("  Q1");
   tft.fillRoundRect(120, 60, 50, 200, 8, BLUE); // Q2
  tft.setCursor(20, 20);
  tft.setTextSize(2);
  tft.setFont();
  tft.setTextColor(WHITE);
  tft.setCursor(125, 115);
  tft.print("  Q2");
   tft.fillRoundRect(180, 60, 50, 200, 8, BLUE); // Q3
  tft.setCursor(20, 20);
  tft.setTextSize(2);
  tft.setFont();
  tft.setTextColor(WHITE);
  tft.setCursor(185, 115);
  tft.print("  Q3");
   tft.fillRoundRect(240, 60, 50, 200, 8, BLUE); // Q4
  tft.setCursor(20, 20);
  tft.setTextSize(2);
  tft.setFont();
  tft.setTextColor(WHITE);
  tft.setCursor(245, 115);
  tft.print("  Q4");
  tft.fillRoundRect(870, 900, 50, 30, 8, RED); //Return Button
  tft.setCursor(885, 915);
  tft.setTextColor(BLACK);
  tft.print("<-");
  delay(300);
}
void loop()
{
  digitalWrite(13, HIGH);
  TSPoint p = ts.getPoint(); //read touchscreen coordinates
  digitalWrite(13, LOW);

  pinMode(XW, OUTPUT);
  pinMode(YP, OUTPUT);

  if (currentpage == 0)
  {
    if (p.z > MINPRESSURE && p.z < MAXPRESSURE)
    {
      if (p.x > 563 && p.x < 683 && p.y > 275 && p.y < 750) // check if waterchange menu button is pressed
      {
        Serial.println("Waterchange Menu Selected");
        tft.fillRoundRect(60, 130, 200, 40, 8, WHITE);
        delay(100);
        tft.fillRoundRect(60, 130, 200, 40, 8, RED);
        currentpage = 1; //run waterchange menu code
        drawWC(); //open waterchange menu
      }
      if (p.x > 736 && p.x < 855 && p.y > 255 && p.y < 725) // check if monitoring button is pressed
      {
        Serial.println("Water Sensing");
        tft.fillRoundRect(60, 180, 200, 40, 8, WHITE); 
        delay(100);
        tft.fillRoundRect(60, 180, 200, 40, 8, RED); 
        currentpage = 2; //run water monitoring menu code
        drawMonitor(); //open water monitoring menu
      }
    }
  }
  if currentpage == 1 //waterchange menu
  {
    
  }
  if currentpage == 2 // water monitoring menu code
  {
    while (currentpage==2) 
     // call sensors.requestTemperatures() to issue a global temperature 
 // request to all devices on the bus 
/********************************************************************/
 sensors.requestTemperatures(); // Send the command to get temperature readings 
/********************************************************************/
 float TQ1 =  (sensors.getTempCByIndex(0)); // set up variable to read temperature of tank Q1
   tft.setCursor(65,135);
   tft.print(TQ1);
   delay(10000); 
  
  }
}