Sometimes segments are locked for a reason ... such as to prevent major changes being made by someone who doesn't understand the editor system well enough yet. The segment that you permalinked
is already one-way in the correct northbound direction, and has been for over two months at least:
Here's what you might not have picked up on here: when ascertaining what direction a one-way road is going, don't look at the "Direction:" arrow in the Properties box on the left -- look at the arrows on the segment itself in the map view. The "Direction:" arrow just shows whether the segment goes in the direction that it was originally drawn or in the opposite direction -- not which direction the traffic actually flows.
That said, there were some major problems north of there, including the point at the other end of that segment (which was junctioned to nothing, instead of to the next northbound segment in the sequence). Because I corrected that error, the initial segment that you posted about is now showing as having been edited last by me today ... but the direction on that segment is still correct (and has been correct for at least two months, as shown in the screenshot above).
Additionally, there's a major portion of road from that point and northward that should be Freeway rather than Major Highway or Minor Highway (and does I-540 really just end at SE 14th St and continue as a state route only?). I don't have time to deal with that right now and will leave it for a local Area Manager to address.