Sensor Volatage on Display

Hey. Im an Arduino Rookie and have the following problems:

The Signal is flickering on the Display. I wanted to overwrite the Signal every 0,5V. I dont know why i have an permanent 1 Signal on overwrite, although i made some if commands.
Is there any other possibility to reduce the flicker on the display, or do you have any other tips.
Thanks in advance and now my program:

char printout [4];
byte led = 5;
unsigned long previousMillis = 0;
const long interval = 100;
boolean hide = false;
boolean overwrite = false;
#include <TFT.h>
#include <SPI.h>
#define CS 7
#define DC 0
#define RESET 1
TFT screen = TFT(CS, DC, RESET);
void setup() {
// put your setup code here, to run once:
pinMode(5, OUTPUT);

Serial.begin(9600);

screen.begin();
screen.background(0,0,0);

screen.stroke(0,255,0);
screen.text(“VOLT”,0,30);
screen.setTextSize(3);

screen.stroke(255, 0, 0); //Rot
screen.line(0, 0, screen.width(), screen.height());

screen.noStroke();
screen.fill(0,255,0); //Grün
screen.rect(50,20,100,20);

screen.fill(0,0,255); //Blau
screen.stroke(255,255,255); //Weiß
screen.rect(10,45,100,screen.height());

}

void loop() {
// put your main code here, to run repeatedly:

int sensorValue = analogRead(A1);
Serial.println((10.0/1023*analogRead(A1)));
Serial.println(overwrite);

if(analogRead(A1)<900&&(analogRead(A1)>50))
(digitalWrite(led, LOW));
else
(digitalWrite(led, HIGH));

String sensor = String(10.0/1023*analogRead(A1));
sensor.toCharArray(printout, 4);

screen.stroke(0,255,0);
screen.text(printout,0,0);
screen.setTextSize(3);

if(10.0/1023analogRead(A1)==0.00)
overwrite = true;
else if(10.0/1023
analogRead(A1)==1.00)
overwrite = true;
else if(10.0/1023analogRead(A1)==1.5)
overwrite = true;
else if(10.0/1023
analogRead(A1)==2)
overwrite = true;
else if(10.0/1023analogRead(A1)==2.5)
overwrite = true;
else if(10.0/1023
analogRead(A1)==3.00)
overwrite = true;
else if(10.0/1023analogRead(A1)==3.50)
overwrite = true;
else if(10.0/1023
analogRead(A1)==4)
overwrite = true;
else if(10.0/1023analogRead(A1)==4.5)
overwrite = true;
else if(10.0/1023
analogRead(A1)==5)
overwrite = true;
else(overwrite=false);

if(overwrite=true){
screen.stroke(0,0,0);
screen.text(printout,0,0);
screen.setTextSize(3);}
else
screen.stroke(0,255,0);
screen.text(printout,0,0);
screen.setTextSize(3);

Did you forget to post some of your code ?
Did you forget to put code tags (</>) around the code you posted ?

 if(10.0/1023*analogRead(A1)==0.00)

Using equality with floats has the potential of causing problems. Float data types are not stored exactly. What I mean is that 0.00 may actually be stored as 0.000001 which is not equal to 0.000000. This may not bear on the flicker problem, but I thought you should know.

Okay thanks. What can i do instead?

What can i do instead?

That depends on what you want to do. In your case I would not convert to float volts and compare. The analogRead function returns an int data type which is safe to compare with ==. 0.5V is 102 returned from the ADC, 1V is 205 and so on ((unknown voltage / analog reference voltage) * 1024 = ADC counts, [1.5/5]*1024=307).