How do i disable/enable "Worksheet Move or copy" option?

[Saon]

When I have more than one excel windows opened I can move/copy worksheets
from one workbook/file to other by right clicking the worksheet and select
"Move or copy" option. But one of my colleague cant do that as the opened
workbooks are not shown when he selects the "move or copy" option. Is there
any settings from where we can enable/disable this "Move or copy worksheet"
option??

 

[Spiky]

When I have more than one excel windows opened I can move/copy worksheets
from one workbook/file to other by right clicking the worksheet and select
"Move or copy" option. But one of my colleague cant do that as the opened
workbooks are not shown when he selects the "move or copy" option. Is there
any settings from where we can enable/disable this "Move or copy worksheet"
option??

Well, Protect Workbook disables the copy/move function. Not sure if
that is the issue here, since even a protected file should still be
seen in the Copy/Move window.

Could he somehow have Excel opened twice, so the workbooks don't "see"
each other? Or, I find people who don't understand computers often
make mistakes they don't even realize....so, are you sure he actually
has more than one file open?