Basically, you can either include:
"plugin" : true,
"img" : "http://cdnbakmi.kaltura.com/content/uiconf/ps/demos/kdp3/assets/coffee.png",
"href" : "http://kaltura.com",
"title" : "my logo"
"inlineScript" : false
in all your embed codes or you can use the uiConf API, first calling list() with KalturaUiConfFilter objTypeIn = '1,8' to get all the player IDs, then calling get() on each to obtain the current JSON config [the 'config' member of the KalturaUiConf object], then change the value so that the logo plugin has your desired values and finally, calling update() passing the new config.
I recommend you call get(), modify the config and update() on one test player before iterating on all players.