GPT .xslx loading worked with GPT4-Turbo but not with GPT4o

My GPT worked fine on GPT4-Turbo but not on GPT4o. The context window helps it write better and longer code but it finds it hard to interact with files. Is there a way to make my GPT use Turbo instead of 4o? If not, does anyone know if there is a new way for it to load & return .xlsx files to users?