I tried to use Softaculous to update Joomla 1.5.23 to joomla 1.5.26, and was offered a full install of Joomla 1.5.26.
I was unable to accept this offer because some of the Joomla files had been extensively customized, especially the template.
I therefore manually upgraded 1.5.23 to 1.5.24, then 1.5.24 to 1.5.25 and finally 1.5.25 to 1.5.26 by unzipping the package update files. Thes updates were successful and Joomla is now version 1.5.26.
However, Softaculous still thinks that I am using Joomla 1.5.23 so it tells me I have one update.
When will Softaculous realize that I am already uptodate at version 1.5.26 ?
This is because you have manually updated the installation and hence Softaculous does not know that the installation is up to date.
The solution for this is that just click on the blue Upgrade link on the Joomla page this will redirect you to Upgrade and before you click on the Upgrade button you will see a Yellow Notice stating that the current version and the installed version is not same. Just click on the notice and it will Update the Softaculous records.