Excel ran out of resources

I'm using MS 365 on my mac and I'm now getting 'Excel ran out of resources while attempting to calculate one or more formulas. As a result, these formulas cannot be evaluated'

I have looked at errors in formulae and cleared one that was not happy. All of the help discussions are telling me to go

1. Go to the File menu.
2. Select options.
3. Go to the Advanced tab in the Excel options dialog box.
4. Go to the formulas section and select the manual option for the number of calculation threads. Then set the number of processors to 1.

but this is not possible in MAC

Can anyone help? Thanks