I am in creative in a world I worked hard on but the normal is survival and I can still get achievements

So I logged into a world I have spent 170 hours on and was in creative I can still get acheivement and the defualt gamemode is survival if you could maybe release a update that makes it possible toset your personal gamemode without the defualt being creative or I could send you the file if needed and you could maybe work your magic and get me in survival PLEASE I really dont want to start over as I have spent a lot of time on it and gotten every achievement in the world please help me I have not used any cheeting apps but a friend might have when he played on my phone so appologies if this is the problem but please help in any case if possible