Xiaobaitu, is it 100% safe to use AVR from CA to US?

Xiaobaitu and experts,

I changed J to F without leaving the US. I need to go to Canada next month. How safe is it to use AVR? What questions might be asked? Could it be possible to have any troubles? Just to get fully prepared for reentering the US without being turned down. If being turned down, then I\'ll lose everything in the US. Sad...

Thanks a lot!