Changing Label of Abstract Submission Form

Which file do I need to edit in order to change the label Contribution type to Presentation type in the Submit new abstract form that pops up?

While you could do that, such changes would go away with every update (and no, not updating to new Indico releases is NOT an option).

In the abstract submission form the string is here:

But again, I strongly recommend against this.

Many thanks for the swift response. I shall advice the client to just use the current label as it is.