You can update your email address on the Account Settings page:
I tried and tried, but I can't and get thsi message :
"Ce champ doit être unique.".
The email adresse on that page is an old one, I can't even open it. Could you help me please?
I am not Marlene666 who asked for, but I have the same issue.
Based on that error message you see, you can't change email address because you already have other account created with email you want to use.
You can message me on support(at)lingq.com and I will look into it for you.
Thank you. I will.