I've been using TFS at work a lot, but now created it for my own purposes.So, my questions are:
I searched a lot, but haven't found any answer. Renaming columns of the backlog board view (inside Stories - Board) is easy - just clicking on column is enough to rename it, however this doesn't work for sprint view.
Question 1:
If you mean to rename the column as below:
It's not able to rename it for now. Just as you said, you could only modify the backlog board, but not the board for iterations.
Question 2:
For on-premise TFS, you need to export the process config, edit the xml to rename the Features backlog to the name you want, import the process config back.
More detail step please take a look at this blog: Renaming the Features Portfolio Backlog to Epics
How to modify/update the ProcessConfiguration.xml ,you could also refer Update ProcessConfiguration to add the Initiative portfolio backlog
For VSTS, you could rename it by customizing your backlog, how to please refer: Edit, rename, or delete a portfolio backlog
