Based on your photo the board is at a steep pitch. To be able to even start to foil the board needs to plane off. The rider in the photo is almost hanging ten so it would be very challenging to shift any more weight forward.
Different battery is warranted but you should also move the motor so it is attached to the trailing edge of the mast.
There are lots of photos posted here about the various approaches to making a “clamp” for the motor mount. Some are 3D printed and if you don’t know how to make in yourself you can likely find someone who could print it for you. The “3D files” are frequently posted so all you need to do is download the correct one
Other “clamp” designs use metal to accomplish the same goal.
The “clamp” needs to be sized for your particular motor and the mast it’s attached to.
In addition to the clamp part you should also acquire a “nose cone” that goes over the clamp so that water will flow past your motor better. Every bit helps.
Some people have 3D printed wire guides for the mast trailing edge that improve the hydrodynamics to some extent.
Most users here route the wires inside the mast for this reason. Just as a reference point I started with my motor wires external and enclosed them with wire guides. I recently routed the wires inside the mast and saw a 30% increase in max speed and ride duration. The general ride handling is also much better but that is more opinion than a measurable variable.
Lots of good info here. Use the search function and do lots of reading.