Choice workflow variable how do I set the choice options?

HI,

The Choice variable is used to set a single choice on a choice column. You do not store all choices in the variable as the available choices are already configured in the column.

Thanks @SimonMuntz 

Different to how I thought it would be used.

 

I'm just a bit too familiar to the experience of the SharePoint on-premise workflow variables.

 

Oh my mistake sorry. I didn't realise you wanted to show the variable on a start form.
To do this in O365 you have to create a choice variable and then tick the Initiation check box and a yellow cog will appear. Click the cog and you will be able to enter the choices.