Everytime I try to mod my profile on horizon it corrupts how do I stop it from corrupting?
Redownload your gamertag.
Is there a way to save the mods I did?
If your profile is corrupt its best to start from the beginning.
Next time dont overdo the modifications to your profile, might be why its corrupt now.
Okay thank you for your help. 
I only moded one thing this time and it still corrupted my profile…
What did you do?
I add Black flag to my profile.
So you used the game adder and reashed and signed?
Yeah.
It give’s me a .bak file with the original.
Just to check, did you do this like on the profile:
No should I do it like that?
Yeah, maybe start from 1:20 in the video tho.
Because the first part is just his way of getting hos profile into Horizon,
I might be to late but I made a video showing how use the game adder in the newest version of horizon.