If you’ve imported one of your designs from previous games and want to edit it, you have to load it onto the car first … then you can edit it and save or share or whatever from there.
Are you sure it’s the exact same car? Year, model, make, etc.? For example, a paint on a Forza Edition car won’t work on the standard version of the same car. Some models do change slightly from game to game. If it changes in any way, the imported paint won’t work.
One additional note … just to check. You are actually ‘in’ the car right? You have to be in the car to load a design file.
I imported a livery for the standard escort rs cosworth and I went to pick car and selected standard escort rs cosworth. All I get is share or rename.
I can apply a livery and make changes to my Lancia though.
Pretty sure you don’t get the option to apply it to your current car as you import it, you have to find it again under the Forza Horizon 4 designs tab afterwards and apply it from there… Or it may be that you used a manufactuer decal that is not in the game anymore, but in that case I think an alert message would pop up.
Import it, but then get into the car required and apply said livery…
BUT, I would then go into the livery editor, as I’m finding that 90% of imported work shifts on one plain or another so will need tweaking!