We would recommend stripping off any existing wax or sealant such as your Liquid Glass.
Since our Liquid Wax durability is so long (only need to apply 1-2 times per year), it should be the very first product applied to your vehicle. That means removing any previous wax/sealants/polishes that you may have, either with clay bar or a wax stripper such as dawn dish soap mixed with water.
If you apply our Liquid Wax over top another product, it will cause the Liquid Wax to degrade at the same rate. You say you have some layers of Liquid Glass on your vehicle, but definitely this has degraded over time.
Liquid Glass was definitely a good product for it's time, but that has been out on the market for many years... Science and technology in the detailing world has advanced quite a bit over the years, and our Liquid Wax is a result of that.
Our Liquid Wax is brand new and contains newly patented polymer additives that work to extend longevity and enhance the shine.
Our recommendation is to strip everything off, put the Liquid Wax first, then spray something on top of it, such as our Hybrid Wax, once the Hybrid Wax starts the degrade, the Liquid Wax will still be there.
-- Then you just top it again with a new layer of Hybrid Wax.
And for your reference, you can see all our available products here: CarGuys Amazon Store