How did you configured header? It looks like it does not printing from template. If you want you can cancel header and include it into template like…
[LAYOUT]
<C10>RESTORAN KHI TEN
<C00>(0344384-M)
<C00>99.JALAN BERINGIN, TAMAN MELODIES
<C00>80250 JOHOR BAHRU, JOHOR
<C00>Tel: 07-3349495
<C00>GST NO: 001762811904
<C00>
<C10>TAX INVOICE
.... rest of template
You’ll notice <C10> tag both defines position and font size. You can get more info from this tutorial.
… also I’ve corrected your post to fix how your template appears. Please read this post to learn how to properly format your templates while posing in forum.