Springs don't control bouncing, that's the shock absorbers' job. Adjusting the original type shocks just changes the spring preload, there's no damping adjustment. The stock rear shocks are marginal when new - and they wear out fast. So the best results are usually from replacing them with decent ones: Hagon or Ikon are very good but just about any new shock will be much better than the originals or old aftermarket units.
The front forks have pretty simple damping units that wear too, but at least you can tune them a bit by using different weight fork oil. Thicker oil will stiffen up the damping, adding a bit more than stock oil amount will increase the airspring effect when the shock is compressed.
There are also "cartridge emulator" units available for the front forks that improve damping enormously with a DeCarbon damper system replacing the stock rebound only damping orifice unit. These are somewhat pricey and the maker will work out with you the best damping rates for your bike, weight, and riding style... changing the rates afterwards is possible but you need to change the internal shims and spring washers.
The front springs may be tired too, but that doesn't make you bounce. You have two choices here I think - stock or Progressive Suspension.
Riding with worn shocks is not horribly unsafe but it is far from safe. Hit a pothole at speed and you'll hope you can learn to fly - quickly. A bump that rattles your teeth with a good suspension will throw you six feet in the air with an old worn out junk suspension.
Changing the front springs you just block or jack up the front so the tire is unweighted, then remove the big fork cap bolts. To install the emulators you have to dismantle the forks, the wheel and fender must come off.
