1. Why need to update plugins
There are few reasons for updating plugin
First, it is about security. When any expert talks about WordPress security, one of the first things they mention is to install updates. Hackers and other malicious parties watch the release notes. As soon as they learn of a vulnerability, they start exploiting it. So, you need to update as soon as possible to reduce the time that your site is vulnerable.
Second, fix bugs – updates to plugins often fix bugs that were discovered in previous versions.
Third, updates to plugins often add new features and functionality.
2. How to update plugins
Method 1 : Update via administration panel
You will see a message at the top of almost every page of your administration panel.
Step 1 : Go to Plugins tab in your dashboard
Step 2 : Deactive old version
Step 3 : Delete old version by clicking on “Yes, delete this files”
Step 4 : After navigating to Plugins pages, find newest version of plugin.
Step 4 : Click on “Install ”
Step 5 : Then “Active ” plugin after plugin has installed successfully.
Step 6 : Check if version plugin is newest.
Method 2 : Update via sFTP.
Step 1 : First back-up your WordPress site if you haven’t already.
Step 2 : Download a ZIP file of the plugin you need to upgrade. You can usually find most plugins on the plugin repository along with a link to download the newest ZIP file.
Step 3 : Unzip the plugin onto your local machine. It will create a directory called ‘plugin-name’ with all the files under it.
Step 4 : Use sFTP to delete the existing plugin directory from the wp-content/plugins/ directory on your site.
Step 5 : Replace the deleted directory by uploading the unzipped plugin to the wp-content/plugins/ directory leaving it in a directory that looks like (for example) wp-content/plugins/plugin-name
Step 6 : Sign in to your WordPress site. Go to the ‘Plugins’ menu and verify that the plugin you upgraded is the newest version.
You can watch video guiding to do it at below link.