Change Default Name and Password of HC-05 Module with AT Commands

Most important part of the device (HC-05) is above Highlighted Button. 

UNO and HC-05 Connection

• Module RX  - > Uno PIN 11 as TX
• Module TX  - > Uno PIN 10 as RX 
• Module VCC - > Connect UNO 5v PIN OR or UNO PIN 8 (Programmatically it's set to pin mode output and HIGH)
• Module GND -> UNO GND
• MODULE Key Or State Pin - > UNO Pin 9 or Uno 3.3v 

Program :

#include <SoftwareSerial.h>

SoftwareSerial BTSerial(10, 11); // RX | TX

void setup()
{

  pinMode(8, OUTPUT); //for vcc input to module or you can use vcc itself from the UNO  pinMode(9, OUTPUT);  // this pin will pull the HC-05 pin 34 (key/STATE pin) HIGH to switch module to AT mode
  digitalWrite(9, HIGH);
  Serial.begin(9600);
  Serial.println("Enter AT commands:");
  BTSerial.begin(38400);  // HC-05 default speed in AT command more
}

void loop()
{

  // Keep reading from HC-05 and send to Arduino Serial Monitor
  if (BTSerial.available())
    Serial.write(BTSerial.read());

  // Keep reading from Arduino Serial Monitor and send to HC-05
  if (Serial.available())
    BTSerial.write(Serial.read());
} 

KEY THINGS TO REMEMBER:

• Before upload the code please unplug the VCC connection from the module
• Before plug the VCC pin into module press the PUSH the button in HC-05 Module and without releasing the button connect the VCC(5v) Pin to UNO and itself begin to blink the LED on Module slowly.
• Please select the Both NL & CR Option from the Serial Monitor in Arduino IDE.
  
•   COMMAND : AT - Respond = OK
•   COMMAND : AT+VERSION - To Check version.
•   COMMAND : AT+PSWD=12345 - Set the Bluetooth password as 12345
•   COMMAND : AT+NAME=Devopt - Set the Bluetooth Device name as Devopt 
• After completing all these things, remember to unplug the VCC pin from the Arduino board and again plug without pressing push button on HC-05 and try to browse the device in any Bluetooth discover tool (or android phone)