Hello and welcome. I see several things that you are doing wrong.
First, the soil is way too rich. You need to use soil which is mostly rocks. Perhaps 70% to 90% of your mix should be rocks in your climate. I live in WV, and this is my basic mixture. On this side of the Mississippi we have a lot of moisture just in the air. Even if they never get direct rain, this kind of soil retains way too much moisture just from the ambient humidity.
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The soils you buy in the store are incorrect. You can use them as 10% or so of the mix, but you cannot use them alone. Even the ones that say cactus soil. Pumice is by far the best substrate in a SC climate, but it can be difficult to find. You may also use poultry grit or large perlite.
The next thing you are doing wrong is that you are using pots that are way too big. You need relatively smaller pots for cactus and succulents than other plants. This is because water has to drain very fast off the roots, and larger pots take longer to dry.
Third, that Echinopsis is already showing signs of etiolation. I suspect that you are growing it on a covered porch or on a north side of a house. It needs more light than this relatively quickly but not too fast or it will burn because since it has not received correct lighting, it has grown soft. You should never see etiolation but especially not in June/July.
That glaucous Crassulaceaen should never be watered on the leaves. It looks flimsy and weak. It needs much more sunlight. And during the winter it needs a greenhouse or a Mediterranean climate. They are not really indoor plants despite the way they are sold in stores.
I would not personally plant different species of cactus in the same pot. This is begging for problems because they each have very slightly different needs. It also spreads pathogens much more easily.
The Aloe is the only plant I would consider leaving on a covered porch without direct overhead sunshine in summer.
Please change all of these variables if you want to keep these plants long-term. They should each live for decades, and possibly outlive you, if you take the correct care of them. Most people use them as disposable decorations and only keep them for a year or two.
I'm looking for some advice on how to keep my beauties alive. I have potted them into "Miracle grow: moisture control", keep them on my porch that gets a good bit of sun, also have moisture meters. SO any advice on soil or types of cacti they are etc would be great!
