Creating custom skill\talents\modificators and\or in-game notebook.

You can give the opportunity to create their own skills when creating characters. Climbing, cooking and so on. And add the ability to add skills when you transfer characters from campaign to campaign, if you give the opportunity. Or you can just throw a D20 in all situations. But then it would be nice to add....Char-sheet, where GM will bring either their own skills or modifiers. Not everyone can create a software list and quite often created a situation where the players or the masters want to give a character a bonus or penalty to a character or a whole group. In videos about GM mode I do not see the possibility to record data in a "notebook" and save it.

P.S. Sorry for bad English