With this option you can define if the line numbers in the log-file tab gets shown or not.
If this option is checked, the lines in the viewer will be wrapped, so that you will always see the whole line without scrolling.
If "don't delay" is checked, the search will kick in as soon as you type. For bigger files this can be quite disturbing so if you want the search only happen after you finnish writing, you can uncheck this option and adjust the delay to your needs.
Auto Switch Active Tabs
This section allows you to adjust the switch to active tab behavior. The delays are mostly there, to avoid a flickering of the active tab if 2 files are very active at the same time.
Tab min. inactive time
This time says, how long a selected tab needs to stay inactive, before it is allowed to switch away from it.
Min. waiting time after tab switch
This time says, how long it will stay at least on the newly switched tab, before it is allowed to switch away from it again.