Windows 10: I have 2 hard drives, trying to download, one drive is full

Ok so my first harddrive is 100 gb and the 2nd is 900. By default it uses the 100 gb one first. When i try to download something it says disk full. I went to check it out and I learned that my primary is a C drive and secondary is a D drive (i don't know the difference). i saw a setting where i can make new downloads and other stuff save to that D drive so I changed it and it still says disk full. The second one that i want to save to is empty

:)

 

ssd and hard drive

I bought my HP All in one at the MS Store. It has a SSD and hard drive. One is listed as C and one a D, set up by them. When I try to download a lot of pictures I get the message that my drive is full but my 1 TB hard drive is not full. How should it be
configured so that doesn't happen?

 

Switching Hardrive

With My PC I Have Two Hard Drives And One Is 250 Gigabytes And The Other 4 Tb And I Have My Settings Set As All New Files To Save To The 4 TB Because My 250 Gigabyte Hard Drive Is Full, And Every Time i Try To Download Something It Just Says "Disk Full"
And My Operating System Is Windows 10

 

As stated, by default, downloads go to C:\Users\[YourUserName]\Downloads. You can change the default download location at any time. Go to Start/Search and type diskmgmt.msc, Right click the diskmgmt results and Run As Administrator. In the Elevated Disk Management window, in the lower pane, which drive has the most free space. Or go to This PC to view the free space. Attach a screenshot of Disk Management to your next post if you need help.
What Browser are you using? Edge, IE, Firefox, Chrome? In Edge and Chrome, go to the 3 dots (ie) . . . on the upper right of the tool bar, Settings/View Advanced Settings/Downloads/Change change your download location to the Download folder on the drive with the most free space.

 

Are you referring to downloading via your browser? If so, which browser are you using?

By default, many browsers download to the user Downloads folder which is typically on the C: drive. You can move that folder to another drive if you wish, I personally don't bother to move it. I set the browser up so that it doesn't default to anywhere but instead asks me where I want to download the file to for each download. I do that because almost every download I do, I put in a unique place.