How to search and replace in all ducoments?
Easiest and fastest way to do that (and to do most of the things you have asked about) is to refer to the manual.
You can use Edit > Find > Project Replace…but, as indicated, you’ll probably want to refer to the manual for more detailed guidance as it’s quite a powerful function.
Stephen
I would also recommend taking an extra backup before doing a global replace. It’s not only a very powerful function, but also is not undoable. File → Backup → Backup Now.
Katherine
It’s rude for you when you give no answer to any of these questions(which you refered as most of things I have asked about) and blame me for not checking manual.
I am sure you know that I’m not an English native speaker if you checked all my posts.
By the way, thanks for mentioning the manual, I didn’t know there is a manual and only watched the tutorial video for a whole day.
If you are not going to give any advice, then I’m not asking for your advice. 
You might think that folks mentioning the manual is somehow being condescending or unhelpful. Far from it. We are trying to make sure that people who ask questions that can be easily answered know about the resources they have to answer their own questions quickly before they have to completely stop what they’re doing, connect to the forums, put out a question, and wait for the answer.
If there’s something in the manual (or tutorial) that is unclear or confusing, we’re always ready to help clarify. But when you have been here a while and see a bunch of FAQs…you want people to get the fastest, most comprehensive help they can get. And that sometimes includes making sure they know how to help themselves.
At the very least, give folks a search term or section number to go off of so they have an idea of where to start looking. It helps not only that person you’re responding to, but others who may be reading who have the same question.
Try this: Go to the Help menu, type “replace” into the search field there. That will show you any menu item in Scrivener’s menu heirarchy where the word “replace” is used. If you use the arrow keys to highlight that option, it will also illustrate where in the menus you can go to find that option… or just hit enter to invoke that item.
More then 3.5 hours elapsed between asking the question and someone (who has either intuition and / or taken the time to read the manual) replied with a detailed answer. It would have taken a minute to find the answer in the manual, and as the person who did reply noted “you’ll probably want to refer to the manual for more detailed guidance as it’s quite a powerful function”. So the OP still needed to look in the manual, and no part of my advice was in any way wrong or inaccurate.
And the OP knew which term to search for, so there’s no merit in saying I should have told them what to have searched for. And if anyone else has to look in the manual to give the OP the section number to refer to, that is just encouraging the OP and others to ignore all the hours Ioa has put into writing the manual, and it is asking the rest of us to spoon-feed people like the OP. Far better to encourage users to use the app and its comprehensive resources than to infantilise them by insinuating that they don’t have the ability to look in the manual for themselves.
For sure, we all need help from time to time with tricky issues, but something like this is simple to find in the manual, simple to find in the macOS “Help” menu that appears in every single app, simple to find using using the standard “CMD ?” keystroke; and simple for anyone to find if they click on the standard Edit > Find menu bar and just take a few seconds to look.
And the OP said that they didn’t know the manual existed until my post, so by any measure that’s got to be useful for them.
And not being a native English speaker has no meaning here. If the OP can write in English on the forum and read replies in English on the forum, they can also read the English manual. And if they want to write in their own language on the forum, they can. Language isn’t the issue. Lots of us aren’t native English speakers (it’s my seventh language), but people still bother to read the manual or apply some logic to the issue (search and help are standard menu items on all computers).
And it really is okay for users to decide how they want to interact on the forum. We don’t need to police each other all the time. My answer helped the OP to find the manual and presumably answer their own question. No one has yet given a lengthy and detailed answer to the actual question, because to do so would need them to rewrite the relevant section of the manual in their own words, which would be plain stupid. So, again, my answer was right on point: the easiest and fastest solution was to refer to the manual.
If you read the manual and still can’t understand things, then ask. But if you want an easy and fast answer, RTM. It is there for a reason.
It’s even possible to search the forum before posting. Or to use the online resources posted on the L&L website.
I believe in you, Login. I know you can do better.