Upgrade MacBook Pro

Heather, Please do "About this Mac..." from your Apple menu and tell us what that says for your MacBook Pro sub-model. Looks something like this:

That is important to your issue because newer MacBooks Pros allow neither RAM or storage to be upgraded. If we start assuming what model you have, we could give you bad advice.

See the other post.

RAM is like a desktop and storage is like the file cabinet. The bigger desk lets you keep more things active and reduces swapping. Double RAM can easily exceed double performance.

Let the OWC site tell you the real maximum. It may be 8 GB instead of 4 GB.

Website is "macsales.com" which is OWC (OthweWorldComputing). The website sells Mac-related products, including RAM (it has a click-by-click guide to the correct RAM, and has picture guides for replacing RAM and SSDs/hard-disks).

OWC is the best source for all things Mac.

https://www.macsales.com

As Steve says, Apple will not upgrade your RAM. Also, you can probably install more than 4GB RAM.

GeniusBar does not upgrade systems. You need to follow the OWC link in the other post and buy the materials yourself, then follow the instructions OWC provides.