So I want to change one of the columns in my table from string to real. How am I supposed to do that?
Refactor Field in the Processing Toolbox.
Go to Processing > Toolbox > QGIS geoalgorithms > Vector table tools > Refactor fields
This will open the Refactor fields window where you can select the layer that you want to make changes to.
Type drop down choose
Double depending if you want a whole number or a decimal number, respectively, and choose the length.
You can choose to save the new altered layer to a location or if you leave it as default 'Save to temporary file' then 'Save as' the new 'Refactored' layer that is loaded into your project.