I use custom source templates rather than RM's built-in templates for a variety of reasons, not the least of which is that custom templates (i.e., user defined templates) can be modified and the built-in templates cannot be modified. But I have discovered that at least in some cases the templates behave in a very "static" manner. Which is to say, a change to a source template does not seem to take effect for an existing source until and unless the source has been edited, even if no actual changes are made to the source. It seems sufficient to "edit without changing" either a Master Source or a citation as a way to fix the problem.
For example, I recently made a change to my custom source template for marriages. I added a text variable called [MarriageRecordType]. The old footnote sentence was
Marriage Record: <[MarriagePlace]><, [Year]><; [LicenseNumber]><; [CoupleNames]><, [WhereViewed]><, viewed [WhenViewed]>.
The new footnote sentence is
Marriage <[MarriageRecordType]|Record>: <[MarriagePlace]><, [Year]><; [LicenseNumber]><; [CoupleNames]><, [WhereViewed]><, viewed [WhenViewed]>.
I made the change so I could use the same source template for a variety of different types of marriage records, for example for marriage index records in addition to courthouse marriage records. I think that one of several problems with the built-in templates is that there are too many of them, and many of them differ from each other in very small ways that could have been handled by a switch of some sort rather than with multiple templates. So I try to avoid the same problem with my own templates.
As you can see, the new version of my templates uses the [MarriageRecordType] variable as a value switch that defaults to the value Record so that the default footnote sentence starts out with the string "Marriage Record:" without the quotes, just like the old version of the template. This works fine for new Master Sources based on the new template. But for existing Master Sources based on the new template,the footnote sentence starts out with "Marriage [MarriageRecordType]:" without the quotes. To get footnote sentences for existing sources to look right, you have to edit the Master Source or one of the citations even if you don't change anything. Curiously, if you merely look at the footnote sentence for an existing source without editing it, it appears to be correct. It's only when you actually run a report and look at the actual footnotes that the footnotes are incorrect.
I have this vague recollection that this problem has been reported before and even that maybe Tom has an SQLite script that will fix it. But if so, I can't find the previous report of the problem. For the time being, I have few enough Master Sources based on my source template for marriages (maybe a couple hundred of them) that I will just edit each one very briefly, but it sure is irritating.