Yes another question about macro security but maybe a little strange?.

I have a worksheet on a friends computer that has macros, one day we fired up the spread sheet and instead of choosing to enable macros we chose to dis-able them.

Now I have read about going to the security level and changing it but here's the strange thing when I go

Tool/Macros/Security

the security is disabled (greyed out)?

Does anyone know how I would go about re-enabling the security feature?.

Help from the experts (as clearly the there are many here) would be greatly appreciated I cannot find the answer anywhere.

Regards

Ade