Inno Setup - Automatically uninstall old version before installing new version - Path Issue

I am trying to utilize the installer to automatically uninstall an old version before installing the new version of the software.

I did find the following solution somwhere, unfortunately this only seems to work when installing the new software into the same path where the old software was installed. I did chose a new "DefaultDirName", however, when utilizing the code block below, my application will be installed in the old path and the "DefaultDirName" is beeing ignored. The AppId of the old and new version are identical.

Any hint or suggestion how to change the code block is really appreciated!

In Short: Used the code mentioned before, old application will be uninstalled just fine, however the new path defined in "DefaultDirName" for the new application is beeing ignored and the new software is installed into the old path.

Edit: The code should be enough but since people are already downvoting for not showing the whole code, here it is (i edited the actual paths since those are irrelevant for the question)

#define MyAppName "MyAppName"
#define MyAppVersion "2.0"
#define MyAppPublisher "MyAppPublisher "
#define MyAppExeName "MyAppName.exe"

[Setup]
; NOTE: The value of AppId uniquely identifies this application. Do not use the same AppId value in installers for other applications.
; (To generate a new GUID, click Tools | Generate GUID inside the IDE.)
AppId={{96C0C401-85B1-44AE-8AFA-29792C020331}
AppName={#MyAppName}
AppVersion={#MyAppVersion}
;AppVerName={#MyAppName} {#MyAppVersion}
AppPublisher={#MyAppPublisher}
DefaultDirName=C:\Projects\{#MyAppName}
DisableDirPage=yes
DisableProgramGroupPage=yes
LicenseFile=license.txt
; Uncomment the following line to run in non administrative install mode (install for current user only.)
;PrivilegesRequired=lowest
OutputDir=xxx
OutputBaseFilename=yyy
SetupIconFile=xxx\setup.ico
Compression=lzma
SolidCompression=yes
WizardStyle=modern

[Languages]
Name: "english"; MessagesFile: "compiler:Default.isl"

[Tasks]
Name: "desktopicon"; Description: "{cm:CreateDesktopIcon}"; GroupDescription: "{cm:AdditionalIcons}"; Flags: unchecked

[Files]
Source: "xxx\{#MyAppExeName}"; DestDir: "{app}"; Flags: ignoreversion
Source: "xxx\_internal\*"; DestDir: "{app}/_internal"; Flags: ignoreversion recursesubdirs createallsubdirs
Source: "xxx\assets\*"; DestDir: "{app}/assets"; Flags: ignoreversion recursesubdirs createallsubdirs
Source: "xxx\data\*"; DestDir: "{userappdata}/zzz/data"; Flags: ignoreversion recursesubdirs createallsubdirs
; NOTE: Don't use "Flags: ignoreversion" on any shared system files

[Icons]
Name: "{autoprograms}\{#MyAppName}"; Filename: "{app}\{#MyAppExeName}"
Name: "{autodesktop}\{#MyAppName}"; Filename: "{app}\{#MyAppExeName}"; Tasks: desktopicon

[Run]
Filename: "{app}\{#MyAppExeName}"; Description: "{cm:LaunchProgram,{#StringChange(MyAppName, '&', '&&')}}"; Flags: nowait postinstall skipifsilent

[Code]

{ ///////////////////////////////////////////////////////////////////// }
function GetUninstallString(): String;
var
  sUnInstPath: String;
  sUnInstallString: String;
begin
  sUnInstPath := ExpandConstant('Software\Microsoft\Windows\CurrentVersion\Uninstall\{#emit SetupSetting("AppId")}_is1');
  sUnInstallString := '';
  if not RegQueryStringValue(HKLM, sUnInstPath, 'UninstallString', sUnInstallString) then
    RegQueryStringValue(HKCU, sUnInstPath, 'UninstallString', sUnInstallString);
  Result := sUnInstallString;
end;


{ ///////////////////////////////////////////////////////////////////// }
function IsUpgrade(): Boolean;
begin
  Result := (GetUninstallString() <> '');
end;


{ ///////////////////////////////////////////////////////////////////// }
function UnInstallOldVersion(): Integer;
var
  sUnInstallString: String;
  iResultCode: Integer;
begin
{ Return Values: }
{ 1 - uninstall string is empty }
{ 2 - error executing the UnInstallString }
{ 3 - successfully executed the UnInstallString }

  { default return value }
  Result := 0;

  { get the uninstall string of the old app }
  sUnInstallString := GetUninstallString();
  if sUnInstallString <> '' then begin
    sUnInstallString := RemoveQuotes(sUnInstallString);
    if Exec(sUnInstallString, '/SILENT /NORESTART /SUPPRESSMSGBOXES','', SW_HIDE, ewWaitUntilTerminated, iResultCode) then
      Result := 3
    else
      Result := 2;
  end else
    Result := 1;
end;

{ ///////////////////////////////////////////////////////////////////// }
procedure CurStepChanged(CurStep: TSetupStep);
begin
  if (CurStep=ssInstall) then
  begin
    if (IsUpgrade()) then
    begin
      UnInstallOldVersion();
    end;
  end;
end;

Since you use the same AppId, according to the documentation Inno Setup by default picks up the previous installation folder, and that's a natural behavior.

If you want to override that in newer versions of your installer, you should set UsePreviousAppDir to no.