coordinate system - Reprojecting vector layer in QGIS?

I have a series of layers of lines (shapefiles) in My Project. The CRS of some are different and to merge them they all must have same CRS.

When I use Processing/Toolbox/Qgis_algorithims/Reproject_layer the reprojection only works if it is allowed to save to temporary file somewhere (it will not change the CRS when I reproject if I try to save and replace it in My Project directory);

I must remove the original from the layer list and reproject the temp file (without changing the CRS) to get it into my project and name it appropriately.

Is there a better way to reproject a layer in Qgis?