made all the required changes

[phyBrackets]

`//SPDX-License-Identifier: GPL-3.0

pragma solidity >=0.5.0 <0.9.0;

interface ERC20 {
function totalSupply() external view returns (uint256 _totalSupply);

function balanceOf(address _owner) external view returns (uint256 balance);

function transfer(address _to, uint256 _value)
    external
    returns (bool success);

function transferFrom(
    address _from,
    address _to,
    uint256 _value
) external returns (bool success);

function approve(address _spender, uint256 _value)
    external
    returns (bool success);

function allowance(address _owner, address _spender)
    external
    view
    returns (uint256 remaining);

event Transfer(address indexed _from, address indexed _to, uint256 _value);
event Approval(
    address indexed _owner,
    address indexed _spender,
    uint256 _value
);

}

contract MyFirstToken is ERC20 {
string public symbol = "MFT";
string public name = "My First Token";
uint8 public decimals = 18;
uint256 public override totalSupply;

address public founder;
mapping(address => uint256) private __balanceOf;
mapping(address => mapping(address => uint256)) private __allowances;

constructor() {
    totalSupply = 1000;
    founder = msg.sender;
    __balanceOf[founder] = totalSupply;
}

function balanceOf(address _addr)
    public
    view
    override
    returns (uint256 balance)
{
    return __balanceOf[_addr];
}

function transfer(address _to, uint256 _value)
    public
    override
    returns (bool success)
{
    if (_value > 0 && _value <= balanceOf(msg.sender)) {
        __balanceOf[msg.sender] -= _value;
        __balanceOf[_to] += _value;
        return true;
    }
    return false;
}

function transferFrom(
    address _from,
    address _to,
    uint256 _value
) public override returns (bool success) {
    if (
        __allowances[_from][_to] > 0 &&
        _value > 0 &&
        __allowances[_from][_to] >= _value &&
        __balanceOf[_from] >= _value
    ) {
        __balanceOf[_from] -= _value;
        __balanceOf[_to] += _value;
        // Missed from the video
        __allowances[_from][_to] -= _value;
        return true;
    }
    return false;
}

function approve(address _spender, uint256 _value)
    public
    override
    returns (bool success)
{
    require(__balanceOf[msg.sender] >= _value);
    require(_value > 0);
    __allowances[msg.sender][_spender] = _value;
    emit Approval(msg.sender, _spender, _value);
    return true;
}

function allowance(address _owner, address _spender)
    public
    view
    override
    returns (uint256 remaining)
{
    return __allowances[_owner][_spender];
}

}
`