[VBA] Toolbox show up for end user

[skorpionkz]

Hi all,

I developed some User Forms base application in VBA excel. My question is not related to code.
I am not sure what cause it, but some of end users can see Toolbox, even though then using application and don't even have developer screen opened.

Is there any way to disable tool box, so it not popping up for end users of application?
And why it is pops up at all?

Thank you,
Andrew