Hi, I want to update my progression chart. I want to use my current fitness signature which I have just tested, and retroactively apply those numbers beginning at January 1, 2018 as the numbers would have been similar then. I read some blog posts on how to do it, but I don’t seem to be able to do it. I’ve gone back to the January 1, 2018 activity and tried to change the figures but I can not edit it. Also, how do I fix that signature through a long base training period coming up. Thanks
If you click on the Advanced tab on the Activity Details, you can edit the signature at the bottom of the page. 
Then click the Save/Lock button and it will trickle-down to all newer activities.
Done! thanks. Is my fitness signature now locked? And if so, will my next break-though workout update the signature automatically or do I have to unlock it?
It is only locked for the one activity. Everything will work as before but with your new signature.
Thanks again.