Power App form locale settings?

I have a Power App form connected to a Sharepoint list on a subsite. I'm having issues with the default form showing that I've asked in a separate post.

When the form does show, the regional display of the dates are incorrect. They should be English UK, but are showing as US. They're correct in Power Apps when 'playing' the form for preview. I've checked the regional settings and they are as they should be. Also, it ignores the padding I've set on the dates (date pickers) and combo box controls.

While creating the form:

While using the form in the Sharepoint List: