How to block / prevent the resizing of elements on a lower screen resolution ?

Hi.

I'm Thomas
Sorry for my probably bad english, i'm French...

I will resume my problem by step.


1. Before this problem, i didn't have two monitors, but an only one. there wasn't Firefox's resizing problem.
2. Then, I've bought a TV, plugged on my laptop (HDMI). It has a greatest screen resolution than on my laptop.
3. Now, if Firefox's windows is on my TV : There isn't Firefox's resizing problem...
4. Then, if Firefox's windows is on my laptop, the probem is here : There is a big Firefox's resizing problem...



Indeed, by using an firefox addon, i have this problem
-> By using a firefox extension, its display is truncated, almost hidden.


My question(s) :
Is there a way to prevent this?
Else, Is there a way to make firefox believe that the current monitor has a high screen resolution?


This is 2 screenshot
-> On my TV, no problem : https://i.imgur.com/ByVNQGQ.png
-> On my laptop, problem : https://i.imgur.com/YkldX4K.png


thank you in advance


Greatings