Issue with Date Format during Fill

So, I am currently living in the US but primarily live in Australia, thus I am running two Tiller Google sheets for the two currencies (and combining them once per month). My AUD sheet has the preference set as Australian, therefore the formulas are looking for DD/MM, however the fill puts the transactions into MM/DD format. I always have to manually change the transaction dates in order to get the details to pull through into other tabs.

Any thoughts on how to fix this?