My flowers keep rising to the top of my resin :(

I am really new to using resin (literally started dabbling last weekend) and so far learned a lot (one of my first pieces came out really cloudy and I managed to fix it thanks to a handy Resin Obsession tutorial! Now it shines like glass :3) so thought I would try out a 3D square mould I have to try and set some very tiny flowers inside. My only problem is the flowers all rose to the top! I even waited until 20 minutes or so had passed and tried to push them back down with a cocktail stick with no success (the cocktail stick was coming out thick and gloopy so it was starting to thicken up). In the end I used two cocktail sticks to fish out the flowers and see if it was a resin issue once it set (like I didn’t mix it long enough or something). The square itself set great! So where am I going wrong? I’ve looked at videos and picture tutorials and it looks so easy so why am I totally failing? Any help would be awesome!