To update from one version of Save & Share to another you should first verify that the downloaded installation package is newer than the version currently installed.
Checking your currently installed version
- Click on the Save & Share icon in Outlook's ribbon bar
- Select "Info" from the drop down menu
- Confirm your version, ex. 1.0.21
The download location should indicate the latest available version.
Once confirmed that your new download is the most recent simply double click the msi installation file. When asked to "remove" or "repair", select "repair".
To remove Save & Share you have two options. You can double click the original installation package and select "removal" from the resulting dialog. Alternatively you can access Windows Control panel and uninstall Save & Share from there.