Weft QDA is being actively developed, and versions are periodically released with new features and fixes for bugs. Upgrading Weft should be straightforward, whether you use an installer or are using a source package and have already installed the prerequisites yourself.
There may be more than one 'current' version of Weft available at any time. The stable version, with a version number 1.x.y, where x is an even number, is the most tested and reliable release. This is the one recommended for general use. An experimental version has a version number 1.x.y, where x is an odd number. Experimental versions have the newest features, but may have more bugs, and less documentation. They are intended for people who want to test out the latest features.
The Weft Project File Format (*.qdp) can be read by any version 1.x.x of Weft QDA. Very old pre-release versions of the software - 0.9.5 and below - may not be able read projects created in newer versions of Weft QDA.
Version 0.9.4 experimented with an alternative file format which is incompatible with all other versions of Weft. This version should not now be in use, but if you have a project created in 0.9.4 that you need to use elsewhere, you should consult the version 0.9.5 documentation, which explains how to upgrade.