I used it too.The features and performance of these online apps are highly limited.if you have a bunch of large size images (1 file =1.5 MB) such 20 files=10*1.5 =30mb
.You need to upload 30mb and download around the same size.So 60mb bandwidth is wasted and time is also wasted for upload and...
Its quite hard to watermark photos using word.What i use is this tool called Mass Watermark.I add all my photos to it,type in the watermark/ add my logo.It will watermark all my pics in bulk,it has bulk resize function too.Take a look at this video
https://www.youtube.com/watch?v=TKviwY-4tBY