Created USB stick is always in read only mode

I am using balena (etcher V 1.7.1 (latest version) to create a bootable Xubuntu USB stick.
I have to copy a file (bootia32.efi) to the stick, in / EFI / BOOT /, but I can’t because the files are in read-only mode.
How to do ?
Thanks for your help, sorry for my bad english, I’m froggy.
Bests Regards from France, Philippe

Hello @phil17a,
Can you share what OS you are running Etcher on? I have tried flashing a USB drive using Etcher and was able to write files onto it right away. Usually nothing special needs to be done after you have flashed the drive. If your OS supports the filesystem that the ISO image (in your case Xubuntu) uses you should be able to write files to the USB drive.

Thanks and regards,

Hello Pranav,
Sorry for the delay… And Best Wisches for this new year !
I was running Etcher on Xubuntu 20.04.
I have since reinstalled Xubuntu alone on my computer (XPS 15 7590) by removing Windows 10 and used Multisystem instead of Etcher for my USB drive.
I had no problem writing the file to the USB stick in BOOT directory.
Bests Regards,