7D Changes Modes Far Too Easily

I'm surprised you didn't know what "Bulb" was.
Make sure you know what all of the P, Tv, Av, M controls do.

First thing I do with any camera is learn to feel, find, and use all the buttons in the dark, with no LCD screen displayed.

I personally set up my 7D with the "C" functions to different overall camera settings.
C1 is Tv, 1/1000, auto ISO limited to 1600, with AI Servo, expanded focus point, back button focus, etc.. for birds/wildlife.
C2 is Av f/16, with self timer, exposure bracketing, fixed ISO, all focus points, normal button focus, etc.. for landscapes.
C3 is Av f/4, one shot, full auto ISO, grouped focus points, normal button focus, etc.. for general stuff.

Each setting has its own Picture Style setting too.

So most days I just need to glance at camera and check its on C3, then just rotate the dial to change the aperture as required.

BuckSkin wrote in post #19529917
Maybe...; but, I don't think a hair-dryer would create enough heat to cause the shrink process;

At work, we have since many years concluded that a dedicated heat shrink tube heater is a hair dryer, just with half the power and twice the cost.

Well....., so far ... so good !

I went through a long day of banging around in a wagon seat, this time a team wagon being pulled by a tractor.

I had my dial set all the way against the stop in the last "C" position; a duplicate of my "M" settings and also both other "C" settings.

I switched cameras back and forth many times and I never caught the 7D dial in any position other than the 3rd "C" = huge problem solved.

Seeing as the dial always wanted to get inadvertently rotated in the direction of the"B" and "C" positions, I believe that by being already as far in that direction as it could go that any bumps and nudges came against the stop and the dial did not get rotated.

I highly recommend this fix for any camera that has the non-locking mode dial.

And should it rotate anyway you still have two safe bases before anything really changes.