Updating the plugin can be done in two ways.
The first option is to go to your account page in OIMWC. In there you will find a update button if a new version exists. It will say “Install Update Now [version number]”
Next up we have the normal way all other plugin are updated.
In the left admin side menu you will find “Plugins” and then “Installed plugins”.
Search for “Order and Inventory Manager for WooCommerce”. Under the title you will find the text “Update Now” with a light yellow background color. Click on that link to upgrade the plugin.