How to not have thumbnails overlap in Finder

The setting your refer to, is stored in a hidden Finder file called .DS_STORE

This file is obviously overwritten by your friend’s Mac who obviously uses different settings.

As far as I know, there’s no way (other than perhaps making the file .DS_STORE read only in the USB so your friend’s Mac cannot write the “new annoying settings” to it).

You’ll need to jump into the Terminal (/Applications/Utilities/Terminal.app)

Connect your USB Drive, open Terminal.

In Terminal, type:

cd /Volumes
ls 

You should see your own Macintosh HD (or whatever name your internal drive(s) have) and the USB drive (with the name it might have).

Cd into the USB drive like:

cd MyUSBDrive

if the drive has spaces in its name, you must enclose it between quotes

For example:

cd “My Strange USB”

Once in there, you can perform an ‘ls’ to view the contents of the USB. Do that to make sure it’s the right one. Else go back to cd /Volumes and start over :)

Now adjust the settings in the finder the way you want them.

Done?

Now to change the permissions in the USB drive:

sudo chmod 444 .DS_Store

NOTE: The above command might ask you for your password, that is ok. The password won’t be seen when you type it. Just type your password and press enter. Remember the commands in Terminal are case sensitive.

What does that do?: chmod is a command that changes the permissions of files and/or directories. In this case, since the file is a hidden file from the finder, we have to do the job from the terminal (which can always see hidden things). The numbers (444) are read only for everybody.

If you don’t know what chmod does or how it works (or why 444) I recommend you take a look at the help (man page) for the command. In Terminal type:

man chmod

Will this work? To be honest, I don’t know. I believe it will, but I’m not sure if ACLs are preserved in USB devices. If the USB is formatted with FAT32 (they usually are so Windows can read/write) the above might not work.

Other than that, there’s no magical way to tell finder do this, and do it this way. Because if there’s a .DS_Store file, Finder will read settings from there.

"I wish there was a way to "get inside the Finder's head" and see what it's doing. I've tried running a sample of the Finder process in Activity Monitor, but honestly I don't know what it's doing, much less how to interpret the output."

Taking a sample in Activity Monitor is exactly that: getting inside the Finder's head to see what it's doing. While it may seem like greek, I or others here can interpret it for you. Just post it, or make it available for download or viewing (as they tend to be pretty big).

What version of OS X are you using? In OS X 10.5.x and prior, I believe multimedia content ran within the Finder itself, rather than delegating it off to an agent/helper type process, so then the CPU usage may appear higher. For example, previewing a QuickTime movie might make the 10.5.x-and-earlier Finder spike to 60% CPU, while in 10.6 it might be split to something like 10% CPU for the Finder, 30% CPU to the QTKitHelper background process.

Otherwise, I've sometimes seen the code the Finder uses to calculate the size of the contents of a folder cause temporary CPU spikes. (You'll notice something like TSomething::HFSSizerSomething in the stack trace of a sample). Usually it seems insistent on finishing its calculation even if the view you had open that warranted the calculation has since been closed.

In any case, seeing the sample should help pinpoint the issue along with knowing what context led up to the spike. It'll be easier to explain what taking a sample is doing once we have it in front of us to look at.