Right click on any object and select “Edit”, this will open edit window
Right click on the existing outfit and select “Detach”
Go to “Received items” in your Inventory (ctrl+I), Find received Mesh Template Outfit folder (usually starts with MI96…..), Click on “Models” folder, Select “Mesh” or “FitMesh” folder. Then click on the appropriate size for your shape. Try upper or lower size if one size doesn’t fit. Any size fits your avatar is the right size, they are just naming they do not represent their real life counterparts. The difference between Mesh and FitMesh folder, FitMesh outfits respond to body sliders similar to avatar shape does (For example when you resize your breasts size the outfit’s breast area size would also change, not exactly as the body does but similarly). Mesh outfits don’t respond to body shape sliders.
Find “Alpha mask ” file under “Masks and Alpha Textures”, right click and select “add”.
This is how you wear mesh outfits.