In one of my projects I made something like a poll, but when I leave the project the cloud variables variables turn back into a 0. Am I doing something wrong?

They should save even if your project is unshared.

First, try testing Cloud variables here to see if it's your project's problem or not.

This has been a pretty common problem lately:

Scratch Wiki wrote:

As a temporary fix, cloud variables have switched to using a different polling method, which is more reliable but significantly slower. Furthermore, the polling interval time was increased, to prevent spam. This new method works but may cause cloud variables to “rubber band” and reset to a previous value after it has been changed

(Source)

I'd recommend deleting and recreating the cloud variables if you haven't already tried that. Depending on how complicated your project is, it might be a bit of a pain to reinsert the variables in your code, but it almost always works for me (except when it's a sitewide issue).

It should save them, even if the projects unshared. To fix the problem try the above said solutions

jackson49 wrote:

(#3)
This has been a pretty common problem lately:

Scratch Wiki wrote:

As a temporary fix, cloud variables have switched to using a different polling method, which is more reliable but significantly slower. Furthermore, the polling interval time was increased, to prevent spam. This new method works but may cause cloud variables to “rubber band” and reset to a previous value after it has been changed

(Source)

I'd recommend deleting and recreating the cloud variables if you haven't already tried that. Depending on how complicated your project is, it might be a bit of a pain to reinsert the variables in your code, but it almost always works for me (except when it's a sitewide issue).

Is that still current? The Wiki calls it a “temporary fix”, but it also states that the issue started in October 2016, and the paragraph you quoted has been there since 2017.