Like most people I use Word as my word processing software. You'll find the Find/Replace button if you go to Edit on the top bar, then you're offered Find - which will just find a word - or Replace, which will find a word and then replace it. I use Find and Replace a lot when I'm writing and editing.
1. When writing and I get stuck and want to jump I put XXX and then make the leap. Later on I can Find all those XXXs and then stick in whatever's needed to make the link.
2. When writing I might get an idea for a previous scene. Instead of scrolling back I put XXX and then make a note. Later, I use Find and look at all those notes.
3. When writing I know I've got certain...shall we say, quirks? If I'm stuck for a gesture on the first draft, I often have characters running their hands through their hair. This is fine once, twice maybe, but too many times and all my characters would look like cockatoos. Finding the phrase "running his hand" or "he ran his hand" means I can think of something better.
4. Which do you prefer? She felt as if a sledgehammer had whacked her...or...Bam! A sledgehammer whacked her...or...his words hit her like a sledgehammer. I could go on with different versions of sledgehammering, but the least effective uses "She felt". It's a distancing phrase, it puts the reader at arms length by telling us how she feels rather than showing. Bam! let's us feel the sledgehammer at the same time as she does. As a general rule, all "she felt"s can go, and Find is a useful tool for hunting them down. I also do it with "seemed" and "that" and have done it for adverbs too - type in ly and see how many come up.
5. Names. My characters change names a lot when I'm writing, especially minor ones. And then at the end I go back and check I haven't used similar names - I speak as one whose first draft of her first novel featured Patrick, Pat, George, Gerry and Jenny. It's easy to change names using Find and Replace BUT be careful before you press the OK button. I have changed names like Gus to Nick, and ended up with words like AuNickt and disNickting. Get round it by adding spaces before and after the names, or press the Next button rather than All so you can check each one before you change.
6. If I cut bits out from a draft I stick them at the end of the document so I have them to hand if I either want them back, or think there might be a nifty phrase or bit of dialogue lurking that I can use later. I put *THE END* at the end of the book (which is good for morale) and then cut and paste them after it. (Putting the * * means I don't get mixed up with phrases like 'she thought it was the end of everything'.) That way I can easily find where I am so far, and how much of the whole document is discard.