Yes, as rightly identified by you, it may be a problem with the platform you are using which may lack article tagging options and result in a poor search function. If you can mention the platform you are using I can see if the platform has the functionality.
There are many good knowledge base platforms that help you with instant search, for example, I have been using Document360 it has a google-like search feature that makes the user quickly land on the relevant page. Also, the platform supports article tagging and version control. So when articles are updated the author has the freedom to fork the version which he needs to display.
You can also tweak the search even more with the help of in-built analytics which reports on the most searched keyword, find failed searches, and best-performing articles. So, you can add the relevant article that you wish to display in the dropdown when searching for a particular keyword.
All you need a knowledge management tool and implement the right process to make it effective.
This issue is very common with all Software development companies. Bigger organization use Knowledge management as part of the routine to
Basically, documentation is focused on the following server environments, business rules, databases/files, troubleshooting, application installation, and code deployment.
Here are some good reads on software documentation and knowledge management.
If you are looking for the right tool to start immediately, then try Document360 or book a demo for one to one support