Clutch problem

[ken]

I am just thinking that my clutch has some problem. Everytime when I change gears, I will depress the clutch pedal all the way down. But, I only need to release it a little bit and the clutch start to engage.(car start to move)

And I found that the clutch fluid level is in the middle of the "max" and "min" mark. Should I put more clutch fluid in it? And what sort of fluid should I use to top up? Can it mix with different brands?

Or should I change all the fluid? if so, how to do it?

Thanks!