linux - EXT4 external hard drive for use with multiple systems

I recently bought a external hard drive to store some data on. I use Linux but I am not a power user. If I format the drive to EXT4, is it possible for the permissions to ever screw up and I lose access to my data? I will be plugging the drive into several different linux based computers at work and I frequently hop distros on my main home machine.

I need to make sure I don't lose any data because I overlooked something. I am not familiar with EXT 3 or 4.

So far I have done this :

1. Formatted drive to EXT4


2. ran gksudo thunar and changed the permissions to my user account and all settings to read/write


3. Wrote all the files I need to the drive

I really appreciate any help.