So you have updated all your bids based on the performance of your keywords, great work!
But now you want to increase or decrease volume a bit. Problematic if this function is not available.
Increase or decreasing keyword bids by a percentage is very important if you have spent a load of time going through your account making sure that one keyword is more prominent than another. The above video shows how you can highlight all your keywords and change the bids without losing all your hard work!