Change line length (legato)

I want to change the length of a line. I know how to do this, and I have done it many times but sometimes it just doesn't work, or not work as expected. I don't understand this.
I am a beginning musician and I enter simple pieces of music. I do this to have midi available for play-along practice purposes.

This is how I go about
First I enter the notes. After I have finished, I add the legato lines. Now there are two options, and both do not what I expect.

1. I use the lines palet at the left, and select the legato and draw it to the note where the line should start. It does indeed start a legato line at the selected note. Using +, the end of the legato moves one note. It looks good. But: in the midi files, the notes are not played legato. They are played as if the line isn't there.

2. I select the first note where I want the legato to start. Then I click the legato button in the center top (or + key). Indeed, a legato line appears. The line is of some unpredictable length (sometimes two or three notes, or sometimes a lot of notes). There is no way in which I can change the duration of the legato. I can change the visual length, but not the playing lentgh.

The strange thing is that sometimes the second way works fine, and sometimes it doesn't. The first method never works as expected because it doesn't sound as legato in the midi.

Am I doing something wrong? Is there a better way to achieve simple legato?
Thanks for looking at this,

Willy