Polylang flag

Hi there,

https://www.jardindeboissonna.com

I’m having trouble changing my flag for the english language, it’s now set to Canada. I do not remember how I did it (it was ages ago) but I just remember I couldn’t find a British one back then. I’ve seen in threads that you can upload your own, but I am fairly useless with WordPress and the internet in general and don’t know the first thing about a “root directory”.
I’ve tried to change the settings in the Polylang edit thing, and there is supposed to be a drop down menu for the flag but when I click on it, nothing happens or drops down it just says Canada.
Can anyone help me resolve this or explain in the easiest way possible how to upload ones myself? Cannot stress how new I am to this, therefore all other threads I’ve read have been too complicated for me to understand.
Sorry!!

Thanks in advance

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