It is not possible, in any way, to edit speed limits from the Waze app. The only way to change speed limits is by editing the Waze map in WME (Waze Map Editor).
Reporting an incorrect speed limit via the app generates a UR (User Request) on the Waze Map Editor. However, there are major problems with this. When Waze introduced this feature, the map was rapidly flooded with SLURs (Speed Limit URs). You couldn’t tell which way they user was travelling or whether they were reporting the before/after limit. Bugs in the app mean that sometime the required speed to report isn’t available. Some users just report for the points, regardless of accuracy. Some report advisory limits (eg 30mph for a sharp bend).
After the overwhelming number of reports, Waze removed all the reports from the map. They didn’t remove the ability for people to make reports in the app! So for quite a long time, the reports just went into a black hole.
Now Waze are trying to “cluster” the reports to get something a bit more meaningful. But these reports are only visible to Beta map editors and, frankly, the clustering isn’t working well.
So the reports you are making are only visible to Beta editors and they may well not be much use. 
There are a couple of suggestions that might help you in sorting out speed limits. Personally, I carry a Digital Voice Recorder in the car - when I see a problem I make a quick voice note and sort it out when I get home. If you have a Dashcam, this could also be very useful to go back over a recent journey.
There are also a couple of user-created phone apps that work with Waze to report speed limits. These apps effectively allow you to create a precise and distinct User Report with the speed limit information. You can then go to WME and implement the changes. Note that, as mentioned above, URs do not always show up immediately - they can sometimes take a few days, particularly if there are server delays or they were reported as part of a long drive.
You can find a couple of them here: WURM: Waze Update Request Marker and Waze Speed Limit Button. I can’t tell you much about them because they’re Android only (I have an iPhone). They may even be versions of the same thing, based on reading the first post of one.
Also bear in mind that, as a level 1 editor, you may need to request segments to be unlocked if they are locked above your level.
:mrgreen: