Copying Symbology Across Maps

Genuises of QGIS, hlow do I use the same symbology for all my layers across multiple maps. How I usually make maps for clients is to bring in my geo data base with all my layers, then save each layer in that clients folder so I don't end up with too much in a layer that it slows down my computer.
So even having the symbology I want when I import the layers, it changes it when I export them to the clients folder. I've found the exact symbols I want for each layer and want it to be consistent across all my maps, is there a way to do it? I'm so tired of going through and changing the symbols every time I start a new client. Also, can the same be for labels on some of the layers? Please and thank you!