Is the forum I post a question on random?

No, there is an algorithm that selects which subcategory to place newly submitted questions. If you formulate your question to include keywords relevant to the topic to help your question land in the appropriate subcategory, when you Submit it. Some users even preface their question with one or more words from the subcategory heading (where they want it to land) such as "Polls: <poll or survey question>" or "Dogs: <dog related question>".

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IF your question doesn't land in an appropriate subcategory when you submit it, you may relocate it yourself. Moving your question can be done by clicking Edit (pencil icon for mobile)>Edit category just beneath your question, then selecting the category that's appropriate for the topic.

When you first Post the Question Yes its Random Yahoo places it Based on Key Words used in your Question you can Place it in a Particular Category after its Posted if it does not get it Right 

If its not Correct you can Fix it by clicking on the Edit Button then click Edit Category and Select the Right one for it and click Submit