Take a look at ToolsOptions and check whether R1C1 reference style has been
checked on the General tab

"Sondra" wrote:

The row that runs across the top of my spreadsheet that normally shows A, B,
C, D, etc. has now switched to 1, 2, 3 and so on. I have no idea what was
pushed to change this but I sure hope someone else does because it switched
all my formulas also.