VBA add-in no longer works in Word 2016 - macro error

[paulkaye]

Several years ago, while using Word 2007, I began regularly using a plugin for Word called "VBA Find and Replace". It could well have been one of you guys that helped me with it. Recently I switched to Word 2016, and although the add-in appears in an "add-ins" menu in the Word menu bar, when I click on it I receive the following error:

The macro can't be found or has been disabled because of your macro security settings

If I click on "show help", the following text is displayed:

This message can appear if:
⦁ The macro was deleted from the template.
⦁ The template was not loaded or referenced in the Templates and Add-ins command.
⦁ The macro was turned off by the macro security settings of your system.
If the macro security settings are not allowing the macro to run, you should confirm the origin of the macro to be sure that it can be trusted (contact the developer or the source for the macro). You can then temporarily enable all macros by using the following procedure.
1. Click the File tab, click Options, click Trust Center, and then click Trust Center settings.
2. Click Macro Settings.
3. Under Macro Settings, click Enable all macros.
NOTE: Be sure to change this option back to its original setting after you have run the macro.
If the macro is not accessible because the template is not loaded, click the File tab, click Options, and then click Add-Ins. At the bottom of the Add-Ins pane, select Templates from the Manage drop down list, and then click Go. In the Templates and Add-ins dialog box, click either Attach or Add. If the macro is not in the template, you may need to copy the macro from one template to another. Click the Organizer button at the bottom of the Templates and Add-ins dialog box to start the Organizer utility.

As far as I can tell, everything is in its correct place, and macros are enabled. I simply cannot work out what's going on. I found very few posts on the web, and none of them seem to answer my question.
Any help would be very appreciated.