I increased the disk size by 17 GB, but it still shows 33 GB. How to decide?

Question

linux

I decided to increase the size of the disk to 50 GB. I had 33 GB. I went to Windows to cut off 17 GB of free space. After a successful operation, I went to the kubuntu live disk to add these 17 GB to my 33 GB. Got an error. Tried 2 times - it worked. I went to kubuntu and then to Dolphin. I saw that there is still 18GB of free space, that is, nothing has changed. In the "partition manager for KDE" it is shown that all the same I added these 17 GB. Nipoymu how to make everything ok was as it should.
help.

Answer 1

it's unclear.
What they added, what they did.
It is necessary to indicate which tools performed which operations.
Most likely, the partition was enlarged, but the file system was forgotten to be told about it (for example, sudo resize2fs /dev/sdb3)