Manual proxy selection?


I have to extensively rely on sci-hub for accessing materials. My only problem is, that when accessing different paywalls, I can only switch proxy with the “play” icon on the lower url bar, which changes to an other one randomly. But after finding the right one, and clicking on the site, it immediately switches proxy again and loosing the working one which can access the materials.
For example here is this book:
I can click a chapter and click like a hundred times to find a working proxy on a chapter. But after that if I check an other chapter or try to print it, it switches back to a proxy without access.
No way to manually select which proxy number to use from the pool?