Changing it by console also helped me, because otherwise I would not have been able to migrate my account off of my YunoHost instance.

In case anyone finds this via search, here's how you do that, since tootctl isn't usable without some shenanigans.

SSH into your YunoHost instance as admin (ssh admin@youryunohostinstance.example.com) and become root by running sudo -i.

Save the below script somewhere as tootctl.sh and make it executable with chmod +x tootctl.sh.

!/bin/bash

cd /var/www/mastodon/live && PATH=/opt/rbenv/versions/mastodon/bin:/opt/rbenv/shims:/opt/rbenv/bin:/opt/node_n/n/versions/node/12/bin:/opt/node_n/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin RAILS_ENV=production bin/tootctl "$@"
Now you can easily use tootctl by calling ./tootctl.sh instead. To get to know the options run ./tootctl.sh --help.

To reset your account's password run ./tootctl.sh accounts modify USERNAME --reset-password after replacing USERNAME with your instances username, e.g. replace it with tom if your full username was @tom@social.example.com.

Hope this helps!