Grammatically, all of them are acceptable spellings, but in these specific cases, one word is more usual. Refer to AskOxfordfor reference.
Note: When there are two ways of doing something, we make a rule on it one way with the goal of having complete consistency.
You cannot change the world.
❌ Figure: Bad example – two separated words
You cannot change the world.
✅ Figure: Good example - using these terms in one word
We have a program called SSW Code Auditor to check for this rule.