Step 1
First, make sure that the config is not using a pre-configured shape by setting the option menu_shape in the config to CUSTOM. This allows you to set custom slots for days in the rewards menu.
Step 2
Now, head to the rewards.yml and add the following for every day (check the config.yml to see how many days you have to set). For every day, add day-DAYNUMBER: and replace DAYNUMBER with the number of the day. Then under that section you just created, add slot: SLOTNUMBER where SLOTNUMBER is the number of the slot starting at 0.
Step 3
Once you've done all that, make sure to save all files and reload the plugin by using /daily reload. Check your new, customized menu by performing /daily in-game. If you see all days, then you successfully created your own shape!