Pardon me, but I don't really know what you're trying to say.

My problem is importing the characters into FontForge, not exporting them. I'm not sure what screen you're on and how you got there, as I am relatively new to FontForge and your screen is in French.

I've imported all my uppercase characters with no problem, as they are all of uniform size: https://imgur.com/EfyDwWO

I've begun importing lowercase characters, however, and FontForge is scaling them up to be as large as my uppercase characters: https://imgur.com/9gttVCk

I designed my glyphs in Illustrator, exported them all as individual .SVG files, and imported them one by one into FontForge. This is what they normally look like: https://imgur.com/IFvzKE0

Is there a way to let FontForge in on the relative size differences of these characters? I'd rather not scale them down individually, as this is both time-consuming and I'm worried they will no longer all be precisely the same stroke width.