You've selected multiple worksheets (probably were holding down the
Shift key when you clicked another worksheet tab).

Right-click the active worksheet tab and choose UnGroup Sheets...

In article ,
Bev wrote:

I am working in a workbook with multiple sheets, each sheet requiring the
entry of different data which is calculated within each sheet. When I enter
numbers on one sheet, those numbers are duplicated on other sheets in the
same workbook without my having entered it on the other sheets. What is
wrong?

Thank you.

Bev Boucher