title: Delphi decimal separator issue
body: <p>My application works on system with regional settings where decimal separator is comma. (Delphi 10.1)</p>
  
  <p>I have set dot as decimal separator for my application .</p>
  
  <pre><code>  Application.UpdateFormatSettings := false;
    FormatSettings.DecimalSeparator := '.';
    Application.UpdateFormatSettings := true;
  </code></pre>
  
  <p>This works fine for me.</p>
  
  <p>I have used <code>format('%6.3f', 125.365])</code> function.
  Exe is on for 24*7 on the system..</p>
  
  <p>In the initial phase like 1 or 2 hours format function returns data properly with dot as decimal separator but later on it changes to local settings comma</p>
  
  <p>say <code>12,365</code>.</p>
  
  <p>How does dot changes to comma suddenly? </p>