I actually found a fix for this about 2 months ago, but wanted to test it out for a while to be sure - all good so far! You need to change this for every user that has an email address added to your Hubspot account. Otherwise, you’ll change yours and it’ll be fine, but other users will still have the same issue as the system displays the data diffrently per user. And yes, this affects Sequences the same way etc…
To Resolve:
You need to click on your user icon in the very top-right of the Hubspot window (it either has your picture that you added, or a blank profile), and then click on Profile and Preferences. This opens you on the Basic Info page, where you can choose your Country (just below yoru Name and Lanugage).
It automatically updates to the correct format now, but you use to be able to mix and match. So now if you select United Kingdom it atomatically gives you the following Format: 5 November 2018, 05/11/2018, and 1,234.56
Great new little fix, but still odd how it works, thanks Hubspot 