If you installed your WordPress site on WAMP, you can not upload pictures or documents larger than 2 MB by default. You can’t change this limit in WordPress backend, don’t bother searching for it.
Instead, go to your server (or computer) where WAMP is installed and run it.
You need to adjust PHP parameter „upload_max_filesize“. Luckily, WAMP makes that incredibly easy. Click on its icon in taskbar. Then pick „PHP“, „PHP Settings“, „upload_max_filesize“ and pick your desired size. Changes will apply immediately. That’s it.