Does wearing panty liners every day rly cause bv?i wear (non-perfumed) ones but for only about 8 hours and i change every time i use the restroom.

Makes no difference: There have always been urban myths and old wives' tales about tight clothing and vaginal infections in women. Mostly these concerned yeast, but if there is any connection at all, it is very minor. There certainly is no evidence that panty liners, underwear, or other clothing increase the risk of bacterial vaginosis -- not even a theoretical reason why they might. Don't worry about it.