How to permanently allow macro for a trusted worksheet?

I've created a worksheet which is shared amongst my colleagues with a real simply macro to show/hide rows but everytime either I or one of my colleagues opens it they get prompted to Allow marco - is there anyway for them to permantly allow this macro?

How do I protect sheets but allow macros?

A better way to run macros in a protected worksheet would be to use the UserInterfaceOnly argument in the Protect method, by setting the UserInterfaceOnly argument to True, in the manner:"Sheet1. Protect Password:="abc", UserInterFaceOnly:=True".

How do I add a macro to a trusted location?

In your Office app, click File > Options. Click Trust Center > Trust Center Settings > Trusted Locations. In the Trusted Locations list, select a location, and then click Modify. Make the modifications you want, and then click OK.

You'll want to digitally sign the project. Microsoft's information about how to do that is here: http://office.microsoft.com/en-us/excel-help/digitally-sign-a-macro-project-HA001231781.aspx