Yep profiles on all mine too.
You can switch between profiles and then using a code you can add your (personal) profile to whichever device you want.
If say you were part of a largish family, then you could set up a 'family' profile and leave that as default, but its still easy enough to switch to a personal profile within the app.
The thing that possibly takes the longest is adding your profile to the device, but even that only takes a couple of mins.
You start to sign in on the device, then iplayer will send you a code (I usually get these sent to the iplayer app on my phone*). You then enter that code into the device and your profile is now added to that device. You can delete/swap/rename profiles whenever you want.
*I use my phone for convenience so I don't have to wander off to another room, but it can be anything you already have the iplayer app on. Just wanted to make it clear that its linked to the iplayer app rather than my phone number which it doesnt know.