Okay, I misunderstood you, sorry.
You have at least two options, depending on the situation:
A) If you only need to modify one property, you can turn on the keyframes for that property (for each shape>transform>scale, for instance), and show that property by pressing U on the keyboard. You’ll have to select each scale before changing it, so it only helps you part of the way
B) If you have several properties to change, or just want to make it easier to change one property, make a slider control and connect the properties to it with an expression. Once that is done, you can control a property with a single slider — or a set of sliders if you have several properties connected to them