When I want to see grouped tasks in "today" or other modes I always need to click arrow to unfold the list. This is very annoying to do it every time. How can I organize my groups to see them always unfolded in this modes?
unfortunately, you can't set it up to show unfolded automatically, but please note that all tasks are displayed on any search result page and they're repeated if they are part of a group.
For example, if you have a main task with 2 sub-tasks and all 3 are due today, if you look for "today", each task will be displayed separately - only the parent task will have an arrow allowing you to show the sub-tasks associated with it, but both sub-tasks will be displayed as well. Therefore, the arrow is only a reference to show that there are sub-tasks in a certain task, but if they are also included within the search query - you'll see them separately.