Converting CMYK files to RGB in Indesign

Hi!

So I have two files and one of the files was originally set up as a print file (in CMYK) which I recently changed to an RGB file (changed in Document Settings and changed the Transparency Blend Space to RBG, re-imported all the vector graphics to RGB files) but when I export to PDF (Interactive) the colours still dull into CMYK colours. Exporting to JPEGs work though, it only happens when I export to PDF.

I have also tried to copy and paste the elements from the file into another file which was exporting my colours correctly but it still exports dull (so the other pages are okay but the page from the other file is still dull). I've checked and there's no transparency or drop shadows nor am I using PNGs in the page (it's only text and vector files which are exporting fine in my other files). I'm not sure what I'm doing wrong??