What is the best way to cure a yellow furry tongue! I scrub evry day and it still comes back, what causes it!?

Need a check-up. Could be anemia, could be furry tongue syndrome, could be unusual diet, vitamin deficiency. Go for complete, thorough check-up.
Furry Tongue. If you've already tried daily scrubbing with a tongue scraper (and stopped smoking if you do), and you still have a "yellow furry tongue" , you will need to see a local dentist for a complete medical and dental history and a clinical exam for a solution to your dilemma.
Keep on brushing. Food debris and bacteria frequently can build up on the tongue surface and you are doing the best thing by cleaning you tongue regularly. Be careful about scrubbing too hard. Some medications, dry mouth, sinus or post nasal drip flu or other illnesses can increase the build up. Keep on brushing your tongue.