This may be a stupid question but I can't find an easy way to update details for subscriber lists including adding new fields. For example, let's say I have
Person A, Field A, Field B
and I want to change the content of Field B as well as add a Field C. How do I do this within campaign monitor? I've got thousands on my list and the only two ways I can figure this out are
A) manually add new fields for thousands of contacts (terrible, not an option)
B) do an export of my entire list, add/modify the fields in excel, then reupload the entire list again into campaign monitor (this doesn't seem right though because I'll lose all the historical data on the list I have)
You have to do it through Excel. When you export the .csv file it is basically a snapshot of each subscribers custom field values, when you re-import it, it should just update the values that are changed, including the new information/field you've added.
JohnP is on the money here - you'll have to export your list, append your custom fields, then re-import/overwrite existing values. While you won't lose historical data like clicks and opens (only custom fields will be overwritten), the downside is that if your subscribers' custom fields change while you're doing this work (say, when someone uses the preference center), then these changes will be overwritten.
We have been looking at better ways to manage custom fields, so hopefully we'll see this process improved in the near future - we'll keep you updated on this!