I changed the scaling setting in system settings to 2, and then by good fortune, plasmashell crashed, at which point I saw my changes take effect. However, after I logged out and logged in again, plasmashell had reverted to non-scaled fonts. To workaround this, it is necessary to change the scaling setting again, to a different value (2.2 did not work - bizarrely, it only made the problem worse, not better - but 2.5 and 1.5 did). Reproducible: Always Steps to Reproduce: 1. Change scaling setting to 2 in kscreen kcm 2. Crash or kill plasmashell to restart it 3. Log out 4. Log in again (as the same user) Actual Results: task manager has old unscaled fonts again Expected Results: task manager font scaling should have been preserved I have increased the panel height - not sure if that's relevant. Workaround is as stated above - change scaling setting to something else and then restart plasmashell (without logging in and out!)
Also possibly relevant fact: I had already previously set the font scaling to 2, because I didn't know about the scaling settings dialog.
Also, a strange fact worthy of note: I track my dot files using homeshick and git, and I can clearly see that now that I've set my scaling factor back to 2 and restarted plasmashell, in .config/startupconfig, it's still set to 1.5. This happens every time - it shows the old value.
This occurred because I had previously tried setting the "force font DPI", and due to some out-of-date comment I found on the internet, I thought it had no additional effect, and left it enabled.