i have tried on version 4.95 and 5.0 beta 1

so basically when i hover over a joint and it's meant to go pale, it doesn't do anything and i have to click it first. so that means before i can contract/extend the joint i have to do an extra click.

have tried changing mouse buttons and background click settings.

any help appreciated, thanks

This seems like something that would get fixed after you shut down your computer.
-Try shutting down then trying again.
If it that did not work. v

Delete every version of the game ( Remember back up the files that you want to keep e.g Mods,Replays )
Then re install the one version you like to use.
I'd recommend installing 4.95 since 5 is still beta.
There's also a small chance that your installer is broken so downloading the installer again would be perfect.

Good luck.

I had the same problem once I would suggest you to turn off your pc then turn it on again after like 10-20 minutes if that doesnt work try installing a different version like 4.92 or try to reinstall 4.95