Modify multiple keyframes at once?

Recently, I imported an FBX animation to the roblox animator. But the issue is that the character goes under it self.
I’ve tried fixing the issue by modifying the keyframes but there are way too many and going through every single one of them would take up a considerable ammount of time.
Any solutions?

Could you elaborate on what you mean by the character going under itself?

And unfortunately I don’t think you can edit multiple keyframes at once in Roblox, keyframes are key because they are very specific individual poses that get tweened between. Editing multiple at once is not possible since they are all different, but if it is a looping animation and you edit one frame that is repeated elsewhere then you can copy that edited frame and paste it over each old version and so on.

Besides that, it would probably be much easier to edit the animation in Blender.