I like your software very much, but there are some things, which could be (a little bit) better or usefull.
There is a little problem, when using the 20:1 attenuator, because the threshold shown in the toolbar is only a 20th of the threshold in the oscilloscope-window. Would be nice, when this problem can be solved in the next version, because we always use the attenuator.
Another feature of an older version would be nice too: The possibility to configure the toolbars. We use 12 picoscope 3223 in (vocational) education and in some cases it was helpfull to configure the toolbars so, that only a minimum of adjustments and settings could be used by the pupils.
Another helpfull thing would be the measurement like a normal Voltmeter. For some measurements (e.g. the voltage of a lambda-sensor) it is usefull, to see the actual Voltage in decimals, while the oscilloscope runs with 1s/div.
The behaviour that you have observed is intentional and is related to the function of the probe multiplier.
The scope display y-axis is simply rescaled to account for the reduction in amplitude that will result from a x10 probe, for example. The channel gain is not adjusted and therefore, the actual trigger threshold remains unchanged.
In terms of the toolbars you should be able to use the old files in PicoScope 5, you will at least need a file called test044.ini.
Finally for the meter mode, you can do an add measurements and then increasing the font size ?