Please follow the guide from the link below to upgrade the template.
Once there is a notification on template upgrade, you can process the upgrade for that template by going to Admin CP >> Appearance >> Themes.
Choose the template you want to upgrade and select Edit.
On next page, there will be a prompting on upgrading, click on Update Now and the upgrade will process on automatically until finish.
Additional Backup Steps For Customized Template
If you are using phpFox version 4.6.1 build 3 or older versions and already customized your template in the setting of the template such as changing logo, default photos, colors... You need to perform additional steps as below before and after upgrading the template to make sure you can reserve the changes you applied to your customized template.
1. Before upgrading the template, backup the assets folder at:
.../PF.Site/flavors/name-of-the-template/assets
2. Process on upgrading the template as instructed above.
3. After the upgrade process is finished, replace the backed-up assets folder to the current one.