Apply Default Settings doesnt work on one of my games.

All the tokens are set to whisper, but no matter what option I save in the Default Sheet Settings, I cant change it from whisper. Weirdly if I change it to whisper and save it, the Apply Default Settings dialogue then gives me the option of setting all the tokens to whisper, but doing so doesnt change anything, and it just keeps offering to change everything to whisper.

I was running into an issue like this at one point. It seemed that the settings got messed up in the cookies. Clearing my cookies fixed the Apply Default Settings issues.  Alternately, try a different browser. 

Here are the step-by-step instructions i give in cases like these. See if these help: Note that the whisper settings are attached to each individual sheet, there is no actual game setting. These instructions are for changing the defaults for all the character sheets in the game, then applying the settings to all existing sheets. Note that this will also change your PC sheets - you will have to manually change them to a different setting if one is preferred. Here are the ways to toggle this behavior: Always Whisper Go to the Campaign Settings Page Choose "Always Whisper Rolls" under "WHISPER ROLLS TO GM" in the Default Sheet Settings Save Load your game Go to the settings tab on the right and look under Miscellaneous, where you will find a button that says Apply Default Settings. Press it. Choose to update the Whisper settings. Wait a minute or two for it to resolve. There is a thin easy-to-miss progress bar. Never Whisper There's a bug in the game settings that doesn't recognize "Never Whisper Rolls", possibly because it is trying to write a blank value. The solution is to use Whisper Toggle. The default is public, so once this is set, all rolls should show. Go to the Campaign Settings Page Choose "Whisper Toggle" under "WHISPER ROLLS TO GM" in the Default Sheet Settings Save Load your game Go to the settings tab on the right and look under Miscellaneous, where you will find a button that says Apply Default Settings. Press it. Choose to update the Whisper settings. Wait a minute or two for it to resolve. There is a thin easy-to-miss progress bar. Query Whisper The default is public, so once this is set, all rolls should show by default unless you choose otherwise. Go to the Campaign Settings Page Choose "Query Whisper" under "WHISPER ROLLS TO GM" in the Default Sheet Settings Save Load your game Go to the settings tab on the right and look under Miscellaneous, where you will find a button that says Apply Default Settings. Press it. Choose to update the Whisper settings. Wait a minute or two for it to resolve. There is a thin easy-to-miss progress bar.    7. Have fun!

I've tried different browsers, and also followed @keithcurtis' instructions after finding them on other threads about this problem, but I still have this problem. The default is already set to whisper. If I change it to anything else, the Apply Default Settings dialogue gives me the option of setting everything to whisper, no matter what I actually saved in the default settings. I notice that it also ignores me trying to enable things like "show global save modifier field". I tick the option, press apply, wait for the little progress bar to slowly complete... but nothing changes. Another thing I noticed; when I try and navigate away from the game settings page, the browser always warns me that there are unsaved changes—even though I have pressed the save button. This happens in firefox, chrome and edge.

The settings page is... quirky in saving settings. There are actually three sections (token, compendium, sheet), each with its own save button. Make sure you are pressing the save button for the section you are working on. It will probably give you that warning anyway, but AFAICT, it's important to press the corresponding one.

Yeah I havent even expanded the Game Default Settings or Compendium Settings sections, I'm only changing the Character Sheet Template options, and then pressing the save button below them.

Could you try setting everything to query, applying it, and then following the Never Whisper steps? Kind of grasping at straws here. These steps usually work without issue (other than the noted ones). Unless (and I wouldn't discount this) Roll20 has changed something...