Welcome to PSE and Happy New Year khun ภควรรณ

In reply to your "thank you",

I say "you are (very) welcome".

This is what we usually say when someone says "thank you".

Some other times we may say:

"it's a pleasure",

"Glad to be of some help",

"no worry",

"no problem" / "no problemo" (more American Hispanic style)

;-)