Why wont Excel let me enable macros?

This usually happens when Excel is launched in such a way as to not load add-ins. QuickBooks may launch Excel in this way (which Microsoft considers a feature.) More rarely it will happen when the add-in files have been moved or deleted, or when macros actually have been disabled.

Generally, these options could be disabled by group policy settings controlled by your domain admins, if so, you could hardly to make a change without permission from them. If you are now home alone, try to check your group policy settings. Disable this setting if it is enabled.