By default, Foxit PDF Editor will show a warning message when an application without a valid digital signature attempts to open it. However, if you trust the application, you can add it to the whitelist. Steps are as follow:
- Choose File > Preferences > Trust Manager.
- Click Change Settings in the Open Foxit PDF Editor from applications without valid digital signatures group.
- In the Allowed Apps field, specify the application you trusted, and click Allow. The trusted applications will be listed in Apps group. If you want to remove it from the list, please select it first, and then click Delete.
- Click OK to confirm and apply the setting.