Remove/Add space for particion

I need to know how can I remove space for a determinated partition and then add this space removed to other partition using GParted

I try the only thing I think I can do, remove space from the first partition and then add this space for the second partition.

So first, I go into the settings for the first partition and click on Recize/Move.

Then I'll resize this partition to make free space for the other partition.

Now, I click to check if the operation is applied.

And, right now, I have free space to add to the other partition.

But, when I go into the second partition setup to add this new free space, I can't do it, I can't increase the size/space of the second partition, and I don't know what to do.