I have a field that return Post excerpt. But why cant i go higher value than the previewed post in words ?
My next posts have more than 36 words. Why cant i desides my self how many words ?
It looks like you have stumbled across a usability problem here.
It was even worse on my test site, I previewed a post with only 7 words and then the range slider for the excerpt was stuck at a maximum of 7 words even when I changed to preview posts with more content.
I've created an internal ticket about this for the developers; in my opinion we should remove the slider and just have a free numeric input.
There's not much more for me to do. If you want I can escalate this thread and update you when a Toolset Blocks release contains a change for this, otherwise we can simply close.
The current dev cycle is focused on a series of bug fixes, and the next cycle is focused on usability problems, and this issue is on the board for that cycle. So it isn't yet resolved, but is scheduled to be worked on after the current cycle.
As a workaround you can insert a Classic block and use the Fields and Views button (button with Toolset icon) to insert the post excerpt via shortcode, and you can specify the word or character count there.