To update to the latest version of Fintech you have a few options.
NOTE: Before updating the theme we strongly recommend you backup
your live theme instance first! We also highly recommend you first
conduct updates on a staging/development version of your site to ensure
you conduct a full test of major theme and plugin updates in a safe
environment before going through the same process on your live site.
(Good WordPress hosts like Siteground offer the option of testing theme
and plugin updates in a safe staging environment) - http://www.commercegurus.com/siteground
We also assume in this update process that you have made no changes to the theme files yourself. If you have you will first need to move those changes to a child theme. We include a starter child theme in the main Fintech zip package which can be downloaded from Themeforest. You can read more about child themes here:
http://www.commercegurus.com/2014/09/26/starter-child-theme-captiva-released/
http://codex.wordpress.org/Child_Themes
Note: The theme should always be named 'Fintech' - i.e. do not rename it or the update may not work.
https://wordpress.org/plugins/easy-theme-and-plugin-upgrades/
2.) Download the latest version of the theme from http://themeforest.net/downloads - just the theme zip - not the main zip package with docs etc.
3.) Go to Appearance -> Themes -> Add new -> Upload.
Select the zip file you downloaded in Step 2. Ensure you select "Yes" from the dropdown to confirm you're updating an existing theme (as described here https://wordpress.org/plugins/easy-theme-and-plugin-upgrades/)
4.) Once the theme has been upgraded go to Appearance -> Install Plugins - if any updates to Premium plugins have been included in the update ensure that you install them in this section.